newcomer vs arrival

newcomer and arrival both are nouns.

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

As nouns, arrival is a hypernym of newcomer; that is, arrival is a word with a broader meaning than newcomer:

Other hypernyms of newcomer include arriver, comer.

newcomer (noun)	arrival (noun)
any new participant in some activity	accomplishment of an objective
a recent arrival	the act of arriving at a certain place
	someone who arrives (or has arrived)