outside door vs doorknob

outside door and doorknob both are nouns.

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

outside door (noun)	doorknob (noun)
a doorway that allows entrance to or exit from a building	a knob used to release the catch when opening a door (often called `doorhandle' in Great Britain)