saddle oyster vs oyster

saddle oyster and oyster both are nouns.

Word	Noun	Adjective	Verb	Adverb
saddle oyster	Yes	No	No	No
oyster	Yes	No	Yes	No

As nouns, oyster is a hypernym of saddle oyster; that is, oyster is a word with a broader meaning than saddle oyster:

saddle oyster: thin-shelled bivalve having the right valve deeply notched
oyster: marine mollusks having a rough irregular shell; found on the sea bed mostly in coastal waters

saddle oyster (noun)	oyster (noun)
thin-shelled bivalve having the right valve deeply notched	marine mollusks having a rough irregular shell; found on the sea bed mostly in coastal waters
	edible body of any of numerous oysters
	a small muscle on each side of the back of a fowl

saddle oyster (verb)	oyster (verb)
	gather oysters, dig oysters