pilchard vs clupeid fish

pilchard and clupeid fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
pilchard	Yes	No	No	No
clupeid fish	Yes	No	No	No

As nouns, clupeid fish is a hypernym of pilchard; that is, clupeid fish is a word with a broader meaning than pilchard:

pilchard: small fishes found in great schools along coasts of Europe; smaller and rounder than herring
clupeid fish: any of numerous soft-finned schooling food fishes of shallow waters of northern seas

Other hypernyms of pilchard include clupeid.

pilchard (noun)	clupeid fish (noun)
small fishes found in great schools along coasts of Europe; smaller and rounder than herring	any of numerous soft-finned schooling food fishes of shallow waters of northern seas
small fatty fish usually canned