amphipod vs sandhopper

amphipod and sandhopper both are nouns.

Word	Noun	Adjective	Verb	Adverb
amphipod	Yes	No	No	No
sandhopper	Yes	No	No	No

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

amphipod: a kind of malacostracan crustacean
sandhopper: small amphipod crustaceans that hop like fleas; common on ocean beaches

Other hyponyms of amphipod include beach flea, sand flea, sand hopper, skeleton shrimp, whale louse.

amphipod (noun)	sandhopper (noun)
a kind of malacostracan crustacean	small amphipod crustaceans that hop like fleas; common on ocean beaches