non-poisonous vs nontoxic

non-poisonous and nontoxic both are adjectives.

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

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

Other synonyms of non-poisonous include nonpoisonous.

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