1 Kings 7:26
26 And it was an hand breadth thick, and the brim thereof was wrought like the brim of a cup, with flowers of lilies: it contained two thousand baths.
2 Chronicles 4:5
5 And the thickness of it was an handbreadth, and the brim of it like the work of the brim of a cup, with flowers of lilies; and it received and held three thousand baths.
The account in 1 Kings says 2,000 baths (1 bath is about 6 gallons), but in 2 Chronicles it says 3,000.
I've already highlighted the solution in the passages above. The account in 1 Kings mentions that it typically (at least at that particular time) contained 2,000 baths, whereas we learn from 2 Chronicles that its max capacity was 3,000 baths.
The words aren't the same in English because they aren't the same in Hebrew:
As is often the case, we simply get more detail of an event/object by reading multiple accounts.
Alternatively, we can recognize that if the bath held 3,000 of something, it's also true that it held 2,000 of something, and one account is simply being less precise, because the point of the passage was to establish that it was big, which either number would do.
One author thought it fit to mention how much the pool typically held, the other thought it fit to mention the maximum capacity. The two accounts don't have to contradict at all.