rollmops vs pickled herring

rollmops and pickled herring both are nouns.

Word	Noun	Adjective	Verb	Adverb
rollmops	Yes	No	No	No
pickled herring	Yes	No	No	No

As nouns, pickled herring is a hypernym of rollmops; that is, pickled herring is a word with a broader meaning than rollmops:

rollmops: a pickled herring filet that has been rolled or wrapped around a pickle
pickled herring: herring preserved in a pickling liquid (usually brine or vinegar)

Other hypernyms of rollmops include hors d'oeuvre.

rollmops (noun)	pickled herring (noun)
a pickled herring filet that has been rolled or wrapped around a pickle	herring preserved in a pickling liquid (usually brine or vinegar)