backswimmer vs hemipteran

backswimmer and hemipteran both are nouns.

Word	Noun	Adjective	Verb	Adverb
backswimmer	Yes	No	No	No
hemipteran	Yes	No	No	No

As nouns, hemipteran is a hypernym of backswimmer; that is, hemipteran is a word with a broader meaning than backswimmer:

backswimmer: predaceous aquatic insect that swims on its back and may inflict painful bites
hemipteran: insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis

Other hypernyms of backswimmer include bug, hemipteron, hemipterous insect.

backswimmer (noun)	hemipteran (noun)
predaceous aquatic insect that swims on its back and may inflict painful bites	insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis