migrator vs immigrant

migrator and immigrant both are nouns.

Word	Noun	Adjective	Verb	Adverb
migrator	Yes	No	No	No
immigrant	Yes	No	No	No

As nouns, immigrant is a hyponym of migrator; that is, immigrant is a word with a more specific, narrower meaning than migrator:

migrator: traveler who moves from one region or country to another
immigrant: a person who comes to a country where they were not born in order to settle there

Other hyponyms of migrator include departer, goer, leaver, emigrant, emigre, emigree, outgoer, evacuee, rusher, colonist, settler.

migrator (noun)	immigrant (noun)
an animal (especially birds and fish) that travels between different habitats at particular times of the year	a person who comes to a country where they were not born in order to settle there
traveler who moves from one region or country to another