roamer vs bird of passage

roamer and bird of passage both are nouns.

Word	Noun	Adjective	Verb	Adverb
roamer	Yes	No	No	No
bird of passage	Yes	No	No	No

As nouns, roamer and bird of passage are synonyms defined as:

roamer and bird of passage: someone who leads a wandering unsettled life

Other synonyms of roamer include rover, wanderer.

roamer (noun)	bird of passage (noun)
someone who leads a wandering unsettled life	any bird that migrates seasonally
	someone who leads a wandering unsettled life