migrator vs rusher

migrator and rusher both are nouns.

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

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

migrator: traveler who moves from one region or country to another
rusher: someone who migrates as part of a rush to a new gold field or a new territory

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

migrator (noun)	rusher (noun)
an animal (especially birds and fish) that travels between different habitats at particular times of the year	a person who rushes; someone in a hurry; someone who acts precipitously
traveler who moves from one region or country to another	someone who migrates as part of a rush to a new gold field or a new territory
	(football) a ball carrier who tries to gain ground by running with the ball