slang vs non-standard speech

slang and non-standard speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
slang	Yes	No	Yes	No
non-standard speech	Yes	No	No	No

As nouns, non-standard speech is a hypernym of slang; that is, non-standard speech is a word with a broader meaning than slang:

slang: a characteristic language of a particular group (as among thieves)
non-standard speech: speech that differs from the usual accepted, easily recognizable speech of native adult members of a speech community

As nouns, non-standard speech is a hypernym of slang; that is, non-standard speech is a word with a broader meaning than slang:

slang: informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar
non-standard speech: speech that differs from the usual accepted, easily recognizable speech of native adult members of a speech community

slang (noun)	non-standard speech (noun)
a characteristic language of a particular group (as among thieves)	speech that differs from the usual accepted, easily recognizable speech of native adult members of a speech community
informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar