“This is very interesting; I’d never even heard of residential colleges before.”
Sure you have. You just didn’t know it. The houses at Hogwarts (Gryffindor, Ravenclaw, etc.) operate pretty much the same as residential colleges. The British boarding school houses and university colleges are the model for the residential house/college system in the US.
I don’t think it’s either/or @JeanJeanie . As I understand it, the main difference between dorms and an RC is that the RC stays together for four years, may have its own dining hall and other facilities. A college-within-a-college, if you will, except most do not seem to offer classes (I guess there are exceptions).
Not all residents of residential colleges everywhere stay together for 4 years.
Pretty much all (that I have heard of) have either some academic component to them or at least traditions, however.
Living-Learning Centers also exist.