nonstandard vs substandard

nonstandard and substandard both are adjectives.

Word	Noun	Adjective	Verb	Adverb
nonstandard	No	Yes	No	No
substandard	No	Yes	No	No

nonstandard (adjective)	substandard (adjective)
not standard; not accepted as a model of excellence	falling short of some prescribed norm
varying from or not adhering to a standard
not conforming to the language usage of a prestige group within a community