Ordinary universities (four-year universities) or colleges of arts and sciences usually divide colleges according to the nature of disciplines. For example, the engineering school is the Institute of Technology, the business school is the business school, and the Academy of Fine Arts is the Academy of Fine Arts. The main subjects are included in the college, and the structure is simple, as most schools do.

In a few cases, some schools may form different colleges due to historical reasons, and these colleges may have their own professional colleges. For example, there are several different colleges in UCSD, so although it is the same school in the same place, there may be more than two science colleges or engineering schools belonging to different colleges, and students and professors may be able to communicate with each other, which may also cause different colleges to have different quality because of different resources. But usually this situation is much less than the previous one.

Schools not only refer to colleges, but also refer to general schools, which is less troublesome. However, in addition to the two usages explained here (that is, the special names of liberal arts Colleges and schools), the most common usage of college is of course community college, which many Americans are used to calling junior college. In addition, there is a relatively rare use of residential college, which is a special dormitory system and is common in Ivy League universities and liberal arts colleges.

However, these are just customary terms, and there are no hard and fast rules.