patois vs rhyming slang

patois and rhyming slang both are nouns.

Word	Noun	Adjective	Verb	Adverb
patois	Yes	No	No	No
rhyming slang	Yes	No	No	No

As nouns, rhyming slang is a hyponym of patois; that is, rhyming slang is a word with a more specific, narrower meaning than patois:

patois: a characteristic language of a particular group (as among thieves)
rhyming slang: slang that replaces words with rhyming words or expressions and then typically omits the rhyming component

Other hyponyms of patois include street name.

patois (noun)	rhyming slang (noun)
a regional dialect of a language (especially French); usually considered substandard	slang that replaces words with rhyming words or expressions and then typically omits the rhyming component
a characteristic language of a particular group (as among thieves)