rhyming slang vs vernacular

rhyming slang and vernacular both are nouns.

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

As nouns, vernacular is a hypernym of rhyming slang; that is, vernacular is a word with a broader meaning than rhyming slang:

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

Other hypernyms of rhyming slang include argot, cant, jargon, lingo, patois, slang.

rhyming slang (noun)	vernacular (noun)
slang that replaces words with rhyming words or expressions and then typically omits the rhyming component	the everyday speech of the people (as distinguished from literary language)
	a characteristic language of a particular group (as among thieves)

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