blow fly vs bluebottle

blow fly and bluebottle both are nouns.

Word	Noun	Adjective	Verb	Adverb
blow fly	Yes	No	No	No
bluebottle	Yes	No	No	No

As nouns, bluebottle is a hyponym of blow fly; that is, bluebottle is a word with a more specific, narrower meaning than blow fly:

blow fly: large usually hairy metallic blue or green fly; lays eggs in carrion or dung or wounds
bluebottle: blowfly with iridescent blue body; makes a loud buzzing noise in flight

Other hyponyms of blow fly include Calliphora vicina, greenbottle, greenbottle fly.

blow fly (noun)	bluebottle (noun)
large usually hairy metallic blue or green fly; lays eggs in carrion or dung or wounds	blowfly with iridescent blue body; makes a loud buzzing noise in flight
	an annual Eurasian plant cultivated in North America having showy heads of blue or purple or pink or white flowers