Riesling vs vinifera grape

Riesling and vinifera grape both are nouns.

Word	Noun	Adjective	Verb	Adverb
Riesling	Yes	No	No	No
vinifera grape	Yes	No	No	No

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

Riesling: white grape grown in Europe and California
vinifera grape: common European grape cultivated in many varieties; chief source of Old World wine and table grapes

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

Riesling (noun)	vinifera grape (noun)
fragrant dry or sweet white wine from the Rhine valley or a similar wine from California	grape from a cultivated variety of the common grape vine of Europe
white grape grown in Europe and California	common European grape cultivated in many varieties; chief source of Old World wine and table grapes