* University: Generally larger institutions offering a wider range of undergraduate and graduate programs, often including research opportunities. They typically have multiple colleges or schools within them (e.g., a College of Arts and Sciences, a School of Engineering).
* College: Can be a smaller institution offering primarily undergraduate degrees, or it can be a constituent part of a larger university (as mentioned above).
So, while you might hear someone use the phrase "college university," it's redundant. It's just a way of emphasizing the breadth of offerings of a particular university, implying it's large and comprehensive enough to encompass many different colleges within its structure.