flyover vs fly-by

flyover and fly-by both are nouns.

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

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

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

Other synonyms of flyover include flypast.

flyover (noun)	fly-by (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