fly-by vs flyover

fly-by and flyover both are nouns.

Word	Noun	Adjective	Verb	Adverb
fly-by	Yes	No	No	No
flyover	Yes	No	No	No

As nouns, fly-by and flyover are synonyms defined as:

fly-by and flyover: a flight at a low altitude (usually of military aircraft) over spectators on the ground

Other synonyms of fly-by include flypast.

fly-by (noun)	flyover (noun)
a flight at a low altitude (usually of military aircraft) over spectators on the ground	a flight at a low altitude (usually of military aircraft) over spectators on the ground
	bridge formed by the upper level of a crossing of two highways at different levels