external vs foreign

external is a noun but foreign is not a noun.

Word	Noun	Adjective	Verb	Adverb
external	Yes	Yes	No	No
foreign	No	Yes	No	No

external (noun)	foreign (noun)
outward features

external (adjective)	foreign (adjective)
happening or arising or located outside or beyond some limits or especially surface	relating to or originating in or characteristic of another place or part of the world
coming from the outside	of concern to or concerning the affairs of other nations (other than your own)
from or between other countries	not belonging to that in which it is contained; introduced from an outside source
purely outward or superficial	not contained in or deriving from the essential nature of something