newcomer vs freshman

newcomer and freshman both are nouns.

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

As nouns, newcomer and freshman are synonyms defined as:

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

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

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