froghopper vs spittlebug

froghopper and spittlebug both are nouns.

Word	Noun	Adjective	Verb	Adverb
froghopper	Yes	No	No	No
spittlebug	Yes	No	No	No

As nouns, spittlebug is a hypernym of froghopper; that is, spittlebug is a word with a broader meaning than froghopper:

froghopper: a variety of spittlebug
spittlebug: small leaping herbivorous insect that lives in a mass of protective froth which it and its larvae secrete

Other hypernyms of froghopper include spittle insect.

froghopper (noun)	spittlebug (noun)
a variety of spittlebug	small leaping herbivorous insect that lives in a mass of protective froth which it and its larvae secrete