There’s some detailed scholarly issues about this. It looks like what he have as Chronicles may contains parts of the text that Kings calls Chronicles of the Kings of Judah. (To be precise, what Kings calls Divrei Hayamim and what is commonly translated at Chronicles. The Hebrew title of the extent book of Chronicles is also Divrei Hayamim).
So why do they seem to be distinct books?
First the extant book called Chronicles contains description of events after the time of Kings, so whatever Kings is talking about had at minimum to refer to something else. In particular, Chronicles includes the decision by Cyrus to let the Jews return and Kings ends with events happening about forty years before. (There are some complicating issues- the chronology in both Kings and Chronicles as well as other later books of Tanach doesn’t fit well at all with the Babylonian or Persian records when talking about the time period of the first exile. Exactly which bits are temporally reliable are not clear.) Now, one could say to this that it is possible that the book of Kings actually refers to an earlier version of Chronicles and that our text has sections added at the end. There is, as I understand, linguistic problems with this. In particular, the end of Chronicles_extant uses a pretty consistent language and style, but I don’t know enough about the linguistics to evaluate or comment on that claim in detail.
Second, Kings seems to be referring to multiple distinct books as Chronicles, one for the Judean kingdom and one for the Israelite kingdom. (For most of the First Temple period there are two distinct kingdoms). See for example 1 Kings 16:5, and the verse cited above. And in fact, Chronicles_extant makes a similar pair of references to two books of kings, although it isn’t completely clear that the author is talking about the same thing. See for example 1 Chronicles 9:1 and 2 Chronicles 16:11.
Third, Kings and Chronicles have very different attitudes about the same kings and events, and sometimes gives them different names. See in particular 1 Kings chapter 15 and 2 Chronicles chapter 13 for a glaring example. That strongly suggests that neither source had access to the other source.
There’s some detailed scholarly issues about this. It looks like what he have as Chronicles may contains parts of the text that Kings calls Chronicles of the Kings of Judah. (To be precise, what Kings calls Divrei Hayamim and what is commonly translated at Chronicles. The Hebrew title of the extent book of Chronicles is also Divrei Hayamim).
So why do they seem to be distinct books?
First the extant book called Chronicles contains description of events after the time of Kings, so whatever Kings is talking about had at minimum to refer to something else. In particular, Chronicles includes the decision by Cyrus to let the Jews return and Kings ends with events happening about forty years before. (There are some complicating issues- the chronology in both Kings and Chronicles as well as other later books of Tanach doesn’t fit well at all with the Babylonian or Persian records when talking about the time period of the first exile. Exactly which bits are temporally reliable are not clear.) Now, one could say to this that it is possible that the book of Kings actually refers to an earlier version of Chronicles and that our text has sections added at the end. There is, as I understand, linguistic problems with this. In particular, the end of Chronicles_extant uses a pretty consistent language and style, but I don’t know enough about the linguistics to evaluate or comment on that claim in detail.
Second, Kings seems to be referring to multiple distinct books as Chronicles, one for the Judean kingdom and one for the Israelite kingdom. (For most of the First Temple period there are two distinct kingdoms). See for example 1 Kings 16:5, and the verse cited above. And in fact, Chronicles_extant makes a similar pair of references to two books of kings, although it isn’t completely clear that the author is talking about the same thing. See for example 1 Chronicles 9:1 and 2 Chronicles 16:11.
Third, Kings and Chronicles have very different attitudes about the same kings and events, and sometimes gives them different names. See in particular 1 Kings chapter 15 and 2 Chronicles chapter 13 for a glaring example. That strongly suggests that neither source had access to the other source.