Merlot vs vinifera

Merlot and vinifera both are nouns.

Word	Noun	Adjective	Verb	Adverb
Merlot	Yes	No	No	No
vinifera	Yes	No	No	No

As nouns, vinifera is a hypernym of Merlot; that is, vinifera is a word with a broader meaning than Merlot:

Merlot: black wine grape originally from the region of Bordeaux
vinifera: common European grape cultivated in many varieties; chief source of Old World wine and table grapes

Other hypernyms of Merlot include common grape vine, vinifera grape, Vitis vinifera.

Merlot (noun)	vinifera (noun)
dry red wine made from a grape grown widely in Bordeaux and California	common European grape cultivated in many varieties; chief source of Old World wine and table grapes
black wine grape originally from the region of Bordeaux