unproblematic vs simple

unproblematic is not a noun while simple is a noun.

Word	Noun	Adjective	Verb	Adverb
unproblematic	No	Yes	No	No
simple	Yes	Yes	No	No

As adjectives, unproblematic and simple are synonyms defined as:

Other synonyms of unproblematic include elementary, uncomplicated.

unproblematic (noun)	simple (noun)
	a person lacking intelligence or common sense
	any herbaceous plant having medicinal properties

unproblematic (adjective)	simple (adjective)
easy and not involved or complicated	(botany) of leaf shapes; of leaves having no divisions or subdivisions
	having few parts; not complex or complicated or involved
	easy and not involved or complicated
	exhibiting childlike simplicity and credulity
	unornamented
	lacking mental capacity and subtlety
	apart from anything else; without additions or modifications