red mullet vs mullet

red mullet and mullet both are nouns.

Word	Noun	Adjective	Verb	Adverb
red mullet	Yes	No	No	No
mullet	Yes	No	No	No

As nouns, mullet is a hypernym of red mullet; that is, mullet is a word with a broader meaning than red mullet:

red mullet: brightly colored tropical fishes with chin barbels
mullet: bottom dwelling marine warm water fishes with two barbels on the chin

red mullet (noun)	mullet (noun)
brightly colored tropical fishes with chin barbels	bottom dwelling marine warm water fishes with two barbels on the chin
	freshwater or coastal food fishes a spindle-shaped body; found worldwide
	highly valued lean flesh of marine or freshwater mullet