noncitizen vs traveller

noncitizen and traveller both are nouns.

Word	Noun	Adjective	Verb	Adverb
noncitizen	Yes	No	No	No
traveller	Yes	No	No	No

As nouns, traveller is a hypernym of noncitizen; that is, traveller is a word with a broader meaning than noncitizen:

noncitizen: a person who comes from a foreign country; someone who does not owe allegiance to your country
traveller: a person who changes location

Other hypernyms of noncitizen include traveler.

noncitizen (noun)	traveller (noun)
a person who comes from a foreign country; someone who does not owe allegiance to your country	a person who changes location