nontoxic vs non-poisonous

nontoxic and non-poisonous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
nontoxic	No	Yes	No	No
non-poisonous	No	Yes	No	No

As adjectives, nontoxic and non-poisonous are synonyms defined as:

Other synonyms of nontoxic include nonpoisonous.

nontoxic (adjective)	non-poisonous (adjective)
not producing or resulting from poison	safe to eat
safe to eat	not producing poison