mosquito hawk vs nightjar

mosquito hawk and nightjar both are nouns.

Word	Noun	Adjective	Verb	Adverb
mosquito hawk	Yes	No	No	No
nightjar	Yes	No	No	No

As nouns, nightjar is a hypernym of mosquito hawk; that is, nightjar is a word with a broader meaning than mosquito hawk:

mosquito hawk: mainly nocturnal North American goatsucker
nightjar: mainly crepuscular or nocturnal nonpasserine birds with mottled greyish-brown plumage and large eyes; feed on insects

Other hypernyms of mosquito hawk include caprimulgid, goatsucker.

mosquito hawk (noun)	nightjar (noun)
slender-bodied non-stinging insect having iridescent wings that are outspread at rest; adults and nymphs feed on mosquitoes etc.	mainly crepuscular or nocturnal nonpasserine birds with mottled greyish-brown plumage and large eyes; feed on insects
mainly nocturnal North American goatsucker