In USA, a University is made up of multiple colleges, this typically consists of a "College of Liberal Arts and Sciences" (which is what most people mean when they say "college"), and one or more graduate colleges (e.g. College of Law, Medical School, Business School, etc)
If an institution is referred to as a College, rather than a University, it typically means that it does not offer post-graduate programs for higher degrees (PhD, JD, Md, MBA, MA, etc)