Compare Devrei HaYamim II 22:1-9 and Melachim II 8:25-29 + 9:27-28

(א) וַיַּמְלִיכוּ יוֹשְׁבֵי יְרוּשָׁלַ‍ִם אֶת אֲחַזְיָהוּ בְנוֹ הַקָּטֹן תַּחְתָּיו כִּי כָל הָרִאשֹׁנִים הָרַג הַגְּדוּד הַבָּא בָעַרְבִים לַמַּחֲנֶה וַיִּמְלֹךְ אֲחַזְיָהוּ בֶן יְהוֹרָם מֶלֶךְ יְהוּדָה.

II Chronicles 22:1

(1) And the inhabitants of Jerusalem made Ahaziah his youngest son king in his stead; for the band of men that came with the Arabians to the camp had slain all the eldest. So Ahaziah the son of Jehoram king of Judah reigned.

מלכים ב ח׳:כ״ה

(כה) בִּשְׁנַת שְׁתֵּים עֶשְׂרֵה שָׁנָה לְיוֹרָם בֶּן אַחְאָב מֶלֶךְ יִשְׂרָאֵל מָלַךְ אֲחַזְיָהוּ בֶן יְהוֹרָם מֶלֶךְ יְהוּדָה.

II Kings 8:25

(25) In the twelfth year of Joram the son of Ahab king of Israel did Ahaziah the son of Jehoram king of Judah begin to reign.

The additional information in the Divrei HaYamim source tells us why Achaziah is now king. Usually in the Judean kindgom, the eldest son becomes king, but he and all of Achaziah`s other siblings that could have been king died in battles. The Melachim source tells us which Israelite king was ruling and what year of his rule did Achaziah become king in. Divrei HaYamim usually leaves out the information about the Israelite kings, while Melachim provides information about both the Israelite and Judean kingdoms.

דברי הימים ב כ״ב:ב׳

(ב) בֶּן אַרְבָּעִים וּשְׁתַּיִם שָׁנָה אֲחַזְיָהוּ בְמָלְכוֹ וְשָׁנָה אַחַת מָלַךְ בִּירוּשָׁלָ‍ִם וְשֵׁם אִמּוֹ עֲתַלְיָהוּ בַּת עָמְרִי.

II Chronicles 22:2

(2) Forty and two years old was Ahaziah when he began to reign; and he reigned one year in Jerusalem; and his mother’s name was Athaliah the daughter of Omri.

מלכים ב ח׳:כ״ו

(כו) בֶּן עֶשְׂרִים וּשְׁתַּיִם שָׁנָה אֲחַזְיָהוּ בְמָלְכוֹ וְשָׁנָה אַחַת מָלַךְ בִּירוּשָׁלָ‍ִם וְשֵׁם אִמּוֹ עֲתַלְיָהוּ בַּת עָמְרִי מֶלֶךְ יִשְׂרָאֵל.

II Kings 8:26

(26) Two and twenty years old was Ahaziah when he began to reign; and he reigned one year in Jerusalem. And his mother’s name was Athaliah the daughter of Omri king of Israel.

Divrei HaYamim and Melachim give us two different ages that Achaziah began his rule in: 42 (DH"B) and 22 (M"B). Age 22 seems more logical to assume because if he was 42, he would have been born before his father Yehoram. Rashi quotes sources from the Talmud that explain that the 42 years represents when King Omri's daughter married in to the Judean Kingdom, and the House of Achav ruled all of Israel (the Israelite and Judean Kingdoms).
The additional "מֶלֶךְ יִשְׂרָאֵל" in Melachim explains what kingdom Omri belonged to.

דברי הימים ב כ״ב:ג׳

(ג) גַּם הוּא הָלַךְ בְּדַרְכֵי בֵּית אַחְאָב כִּי אִמּוֹ הָיְתָה יוֹעַצְתּוֹ לְהַרְשִׁיעַ.

II Chronicles 22:3

(3) He also walked in the ways of the house of Ahab; for his mother was his counsellor to do wickedly.

דברי הימים ב כ״ב:ד׳

(ד) וַיַּעַשׂ הָרַע בְּעֵינֵי יקוק כְּבֵית אַחְאָב כִּי הֵמָּה הָיוּ לוֹ יוֹעֲצִים אַחֲרֵי מוֹת אָבִיו לְמַשְׁחִית לוֹ.

II Chronicles 22:4

(4) And he did that which was evil in the sight of the LORD, as did the house of Ahab; for they were his counsellors after the death of his father, to his destruction.

מלכים ב ח׳:כ״ז

(כז) וַיֵּלֶךְ בְּדֶרֶךְ בֵּית אַחְאָב וַיַּעַשׂ הָרַע בְּעֵינֵי יקוק כְּבֵית אַחְאָב כִּי חֲתַן בֵּית אַחְאָב הוּא.

II Kings 8:27

(27) And he walked in the way of the house of Ahab, and did that which was evil in the sight of the LORD, as did the house of Ahab; for he was the son-in-law of the house of Ahab.

The Divrei HaYamim source tells us that Achaziah's mother, Ataliah (who later on in the chapter becomes extremely evil), teaches her son to do bad.
The Divrei HaYamim source and the Melachim source each have different reasons for why Achaziah did "evil in the sight of the LORD": The Devrei HaYamim source say that he was taught to do evil by his mother and his advisors, while the Melachim source says it is because he was from the House of Achav, who was known as an evildoer against G-d.

דברי הימים ב כ״ב:ה׳

(ה) גַּם בַּעֲצָתָם הָלַךְ וַיֵּלֶךְ אֶת יְהוֹרָם בֶּן אַחְאָב מֶלֶךְ יִשְׂרָאֵל לַמִּלְחָמָה עַל חֲזָאֵל מֶלֶךְ אֲרָם בְּרָמוֹת גִּלְעָד וַיַּכּוּ הָרַמִּים אֶת יוֹרָם.

II Chronicles 22:5

(5) He walked also after their counsel, and went with Jehoram the son of Ahab king of Israel to war against Hazael king of Aram at Ramoth-gilead; and the Arameans wounded Joram.

מלכים ב ח׳:כ״ח

(כח) וַיֵּלֶךְ אֶת יוֹרָם בֶּן אַחְאָב לַמִּלְחָמָה עִם חֲזָהאֵל מֶלֶךְ אֲרָם בְּרָמֹת גִּלְעָד וַיַּכּוּ אֲרַמִּים אֶת יוֹרָם.

II Kings 8:28

(28) And he went with Joram the son of Ahab to war against Hazael king of Aram at Ramoth-gilead; and the Arameans wounded Joram.

The Divrei HaYamim source continues with the evil counsel mentioned in the previous pasuk and tells us that Achav was a king of the Israelite kingdom. Also, there is an added ה in the name "יְהוֹרָם" in the Divrei HaYamim source, but this doesn't really change its meaning.
There is a contradiction of peoples that wounded king Yoram at Ramot Gilad. The Melachim source says it was the Arameans, while the Divrei HaYamim source says it was the "Rammim." This could merely be a misspelling of Aramean, or mean the residents of Ramot (Ramot Gilad).

דברי הימים ב כ״ב:ו׳

(ו) וַיָּשָׁב לְהִתְרַפֵּא בְיִזְרְעֶאל כִּי הַמַּכִּים אֲשֶׁר הִכֻּהוּ בָרָמָה בְּהִלָּחֲמוֹ אֶת חֲזָהאֵל מֶלֶךְ אֲרָם וַעֲזַרְיָהוּ בֶן יְהוֹרָם מֶלֶךְ יְהוּדָה יָרַד לִרְאוֹת אֶת יְהוֹרָם בֶּן אַחְאָב בְּיִזְרְעֶאל כִּי חֹלֶה הוּא.

II Chronicles 22:6

(6) And he returned to be healed in Jezreel of the wounds which they had given him at Ramah, when he fought against Hazael king of Aram. And Azariah the son of Jehoram king of Judah went down to see Jehoram the son of Ahab in Jezreel, because he was sick.

מלכים ב ח׳:כ״ט

(כט) וַיָּשָׁב יוֹרָם הַמֶּלֶךְ לְהִתְרַפֵּא בְיִזְרְעֶאל מִן הַמַּכִּים אֲשֶׁר יַכֻּהוּ אֲרַמִּים בָּרָמָה בְּהִלָּחֲמוֹ אֶת חֲזָהאֵל מֶלֶךְ אֲרָם וַאֲחַזְיָהוּ בֶן יְהוֹרָם מֶלֶךְ יְהוּדָה יָרַד לִרְאוֹת אֶת יוֹרָם בֶּן אַחְאָב בְּיִזְרְעֶאל כִּי חֹלֶה הוּא.

II Kings 8:29

(29) And king Joram returned to be healed in Jezreel of the wounds which the Arameans had given him at Ramah, when he fought against Hazael king of Aram. And Ahaziah the son of Jehoram king of Judah went down to see Joram the son of Ahab in Jezreel, because he was sick.

Melachim provides us with some more information that clarifies what is happening in the pasuk, and there are a few grammatical differences. But the most striking difference that in Divrei HaYami, Achaziah is called "Azariah." Later on he is also referred to as "Yehoachaz." Metzudat David says that he had 3 different names.

דברי הימים ב כ״ב:ז׳

(ז) וּמֵאֱלֹהִים הָיְתָה תְּבוּסַת אֲחַזְיָהוּ לָבוֹא אֶל יוֹרָם וּבְבֹאוֹ יָצָא עִם יְהוֹרָם אֶל יֵהוּא בֶן נִמְשִׁי אֲשֶׁר מְשָׁחוֹ יקוק לְהַכְרִית אֶת בֵּית אַחְאָב.

II Chronicles 22:7

(7) Now the downfall of Ahaziah was of God, in that he went unto Joram; for when he was come, he went out with Jehoram against Jehu the son of Nimshi, whom the LORD had anointed to cut off the house of Ahab.

This pasuk, or any variation of it, does not appear in Melachim. Divrei HaYamim is much more focused on spirituality and G-d's role of punishment in the history of the Israelite and Judean kings. The latter point is quite obviously shown in this pasuk.

דברי הימים ב כ״ב:ח׳

(ח) וַיְהִי כְּהִשָּׁפֵט יֵהוּא עִם בֵּית אַחְאָב וַיִּמְצָא אֶת שָׂרֵי יְהוּדָה וּבְנֵי אֲחֵי אֲחַזְיָהוּ מְשָׁרְתִים לַאֲחַזְיָהוּ וַיַּהַרְגֵם.

II Chronicles 22:8

(8) And it came to pass, when Jehu was executing judgment upon the house of Ahab, that he found the princes of Judah, and the sons of the brethren of Ahaziah, ministering to Ahaziah, and slew them.

This exact pasuk also does not appear in Melachim, but the story of Yehu ben Nimshi occurs in Melachim Bet Chapter 9.

דברי הימים ב כ״ב:ט׳

(ט) וַיְבַקֵּשׁ אֶת אֲחַזְיָהוּ וַיִּלְכְּדֻהוּ וְהוּא מִתְחַבֵּא בְשֹׁמְרוֹן וַיְבִאֻהוּ אֶל יֵהוּא וַיְמִתֻהוּ וַיִּקְבְּרֻהוּ כִּי אָמְרוּ בֶּן יְהוֹשָׁפָט הוּא אֲשֶׁר דָּרַשׁ אֶת יקוק בְּכָל לְבָבוֹ וְאֵין לְבֵית אֲחַזְיָהוּ לַעְצֹר כֹּחַ לְמַמְלָכָה.

II Chronicles 22:9

(9) And he sought Ahaziah, and they caught him—now he was hiding in Samaria—and they brought him to Jehu, and slew him; and they buried him, for they said: ‘He is the son of Jehoshaphat, who sought the LORD with all his heart.’ And there was none of the house of Ahaziah that had power to hold the kingdom.

מלכים ב ט׳:כ״ז

(כז) וַאֲחַזְיָה מֶלֶךְ יְהוּדָה רָאָה וַיָּנָס דֶּרֶךְ בֵּית הַגָּן וַיִּרְדֹּף אַחֲרָיו יֵהוּא וַיֹּאמֶר גַּם אֹתוֹ הַכֻּהוּ אֶל הַמֶּרְכָּבָה בְּמַעֲלֵה גוּר אֲשֶׁר אֶת יִבְלְעָם וַיָּנָס מְגִדּוֹ וַיָּמָת שָׁם.

II Kings 9:27

(27) But when Ahaziah the king of Judah saw this, he fled by the way of the garden-house. And Jehu followed after him, and said: ‘Smite him also in the chariot’; [and they smote him] at the ascent of Gur, which is by Ibleam. And he fled to Megiddo, and died there.

מלכים ב ט׳:כ״ח

(כח) וַיַּרְכִּבוּ אֹתוֹ עֲבָדָיו יְרוּשָׁלְָמָה וַיִּקְבְּרוּ אֹתוֹ בִקְבֻרָתוֹ עִם אֲבֹתָיו בְּעִיר דָּוִד.

II Kings 9:28

(28) And his servants carried him in a chariot to Jerusalem, and buried him in his sepulchre with his fathers in the city of David.

The stories in Melachim and Divrei HaYamim of how Achaziah died are very different.
In Divrei HaYamim, Achaziah is sought out by Yehu to be killed, is captured while hiding in Shomron, and then brought to Yehu and killed.
In Melachim, the story is much more complicated. Achaziah realizes he is being sought after, runs away by the way of Beit-HaGan while Yehu chases him. Yehu then commands that he should die while in the chariot, and Achaziah is then killed in his chariot in Maale-Gur, which is near Yivleam. Achaziah flees to Megiddo, and then dies.
In both Melachim and Divrei HaYamim, Achaziah is buried. But in Divrei HaYamim, the reaosn for his burial is explained: that his father was Yehoshafat, who was devoted to G-d and was good-hearted.
It then leaves off that Achaziah does not have offspring to continue ruling the Judean Kingdom.

I hope you enjoyed the comparisons. Divrei HaYamim is a book that most people never even open, and I hope that my sheet has made such a difficult book slightly more accessible to its readers. I hope to make more comparisons in the future!