In Australia "college" can mean two different things.

It can be another word for high school, especially for exclusive, elite private schools. (For example: Brisbane Boys' College.)

It can be a term for a particular type of residence within a university, especially one that provides more than just a room, but also meals and social activities. (For example, Emmanuel College UQ.)

Historically, it also had at least one other meaning. Among boomer teachers I know, I've heard talk of having gone to "teacher's college". So I think it used to be a sort of more specialised educational institution with a narrower focus than a university. But these don't exist anymore, to my knowledge.