freshman vs beginner

freshman and beginner both are nouns.

Word	Noun	Adjective	Verb	Adverb
freshman	Yes	Yes	No	No
beginner	Yes	No	No	No

As nouns, beginner is a hypernym of freshman; that is, beginner is a word with a broader meaning than freshman:

Other hypernyms of freshman include initiate, novice, tiro, tyro.

freshman (noun)	beginner (noun)
a first-year undergraduate	someone new to a field or activity
any new participant in some activity	a person who founds or establishes some institution

freshman (adjective)	beginner (adjective)
used of a person in the first year of an experience (especially in United States high school or college)