challenging vs stimulating

challenging and stimulating both are adjectives.

Word	Noun	Adjective	Verb	Adverb
challenging	No	Yes	No	No
stimulating	No	Yes	No	No

challenging (adjective)	stimulating (adjective)
requiring full use of your abilities or resources	rousing or quickening activity or the senses
disturbingly provocative	making lively and cheerful
stimulating interest or thought	that stimulates