outside door vs exterior door

outside door and exterior door both are nouns.

Word	Noun	Adjective	Verb	Adverb
outside door	Yes	No	No	No
exterior door	Yes	No	No	No

As nouns, outside door and exterior door are synonyms defined as:

outside door and exterior door: a doorway that allows entrance to or exit from a building

outside door (noun)	exterior door (noun)
a doorway that allows entrance to or exit from a building	a doorway that allows entrance to or exit from a building