internal vs external

internal is not a noun while external is a noun.

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

internal (noun)	external (noun)
	outward features

internal (adjective)	external (adjective)
happening or arising or located within some limits or especially surface	happening or arising or located outside or beyond some limits or especially surface
inside the country	coming from the outside
occurring within an institution or community	from or between other countries
innermost or essential	purely outward or superficial
located inward