flying fox vs megabat

flying fox and megabat both are nouns.

Word	Noun	Adjective	Verb	Adverb
flying fox	Yes	No	No	No
megabat	Yes	No	No	No

As nouns, megabat is a hypernym of flying fox; that is, megabat is a word with a broader meaning than flying fox:

flying fox: large bat with a head that resembles the head of a fox
megabat: large Old World bat of warm and tropical regions that feeds on fruit

Other hypernyms of flying fox include fruit bat.

flying fox (noun)	megabat (noun)
large bat with a head that resembles the head of a fox	large Old World bat of warm and tropical regions that feeds on fruit