immigrant vs migrator

immigrant and migrator both are nouns.

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

As nouns, migrator is a hypernym of immigrant; that is, migrator is a word with a broader meaning than immigrant:

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

Other hypernyms of immigrant include migrant.

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