freshman vs newcomer

freshman and newcomer both are nouns.

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

As nouns, freshman and newcomer are synonyms defined as:

Other synonyms of freshman include entrant, fledgeling, fledgling, neophyte, newbie, starter.

freshman (noun)	newcomer (noun)
a first-year undergraduate	any new participant in some activity
any new participant in some activity	a recent arrival

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