limpet vs common limpet

limpet and common limpet both are nouns.

Word	Noun	Adjective	Verb	Adverb
limpet	Yes	No	No	No
common limpet	Yes	No	No	No

As nouns, common limpet is a hyponym of limpet; that is, common limpet is a word with a more specific, narrower meaning than limpet:

limpet: any of various usually marine gastropods with low conical shells; found clinging to rocks in littoral areas
common limpet: marine limpet

Other hyponyms of limpet include Patella vulgata, Diodora apertura, Fissurella apertura, keyhole limpet.

limpet (noun)	common limpet (noun)
any of various usually marine gastropods with low conical shells; found clinging to rocks in littoral areas	marine limpet
mollusk with a low conical shell