outdoors vs outside

outdoors and outside both are nouns.

Word	Noun	Adjective	Verb	Adverb
outdoors	Yes	No	No	Yes
outside	Yes	Yes	No	Yes

As nouns, outside is a hypernym of outdoors; that is, outside is a word with a broader meaning than outdoors:

Other hypernyms of outdoors include exterior.

As adverbs, outdoors and outside are synonyms defined as:

Other synonyms of outdoors include alfresco, out of doors.

outdoors (noun)	outside (noun)
where the air is unconfined	the outer side or surface of something
	the region that is outside of something

outdoors (adjective)	outside (adjective)
	relating to or being on or near the outer side or limit
	located, suited for, or taking place in the open air
	leading to or from the outside
	originating or belonging beyond some bounds
	functioning outside the boundaries or precincts of an organized unit
	coming from the outside
	from or between other countries
	(of a baseball pitch) on the far side of home plate from the batter
	on or toward an outer edge
	unlikely to occur

outdoors (adverb)	outside (adverb)
outside a building	outside a building
	on the outside