college student vs university student

college student and university student both are nouns.

Word	Noun	Adjective	Verb	Adverb
college student	Yes	No	No	No
university student	Yes	No	No	No

As nouns, college student and university student are synonyms defined as:

college student and university student: a student enrolled in a college or university

college student (noun)	university student (noun)
a student enrolled in a college or university	a student enrolled in a college or university