vernacular vs patois

vernacular and patois both are nouns.

Word	Noun	Adjective	Verb	Adverb
vernacular	Yes	Yes	No	No
patois	Yes	No	No	No

As nouns, vernacular and patois are synonyms defined as:

vernacular and patois: a characteristic language of a particular group (as among thieves)

Other synonyms of vernacular include argot, cant, jargon, lingo, slang.

vernacular (noun)	patois (noun)
the everyday speech of the people (as distinguished from literary language)	a regional dialect of a language (especially French); usually considered substandard
a characteristic language of a particular group (as among thieves)	a characteristic language of a particular group (as among thieves)

vernacular (adjective)	patois (adjective)
being or characteristic of or appropriate to everyday language