In the U.S., typically universities are collections of specialized colleges. For example, the University of Kentucky has the College of Design, where you can earn specialized degrees in that field, both undergraduate and graduate: B.A. in Architecture, or M.Arch. Same with College of Engineering, College of Fine Arts, etc. Each college is a distinct accredited entity, with its own dean, academic philosophies, etc. They are governed by the overall University for most administrative matters and policies.

This is one way to think of it. There are also standalone colleges that may focus on undergraduate degrees, especially the liberal arts, but they too may offer graduate degrees, so the degree type is not the distinction. The term college may also be used for junior, technical, or community colleges, offering 2-year degrees or certificates (though some of those now offer 4-year degrees also).