rhyming slang vs slang

rhyming slang and slang both are nouns.

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

As nouns, slang is a hypernym of rhyming slang; that is, slang 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
slang: a characteristic language of a particular group (as among thieves)

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

rhyming slang (noun)	slang (noun)
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)
	informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar