basil vs sweet basil

basil and sweet basil both are nouns.

Word	Noun	Adjective	Verb	Adverb
basil	Yes	No	No	No
sweet basil	Yes	No	No	No

As nouns, basil and sweet basil are synonyms defined as:

As nouns, sweet basil is a hyponym of basil; that is, sweet basil is a word with a more specific, narrower meaning than basil:

basil: any of several Old World tropical aromatic annual or perennial herbs of the genus Ocimum
sweet basil: annual or perennial of tropical Asia having spikes of small white flowers and aromatic leaves; one of the most important culinary herbs; used in salads, casseroles, sauces and some liqueurs

Other hyponyms of basil include common basil, Ocimum basilicum.

basil (noun)	sweet basil (noun)
leaves of the common basil; used fresh or dried	leaves of the common basil; used fresh or dried
any of several Old World tropical aromatic annual or perennial herbs of the genus Ocimum	annual or perennial of tropical Asia having spikes of small white flowers and aromatic leaves; one of the most important culinary herbs; used in salads, casseroles, sauces and some liqueurs