extraneous vs external

extraneous is not a noun while external is a noun.

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

As adjectives, extraneous and external are synonyms defined as:

Other synonyms of extraneous include outside.

extraneous (noun)	external (noun)
	outward features

extraneous (adjective)	external (adjective)
not belonging to that in which it is contained; introduced from an outside source	happening or arising or located outside or beyond some limits or especially surface
not pertinent to the matter under consideration	coming from the outside
coming from the outside	from or between other countries
not essential	purely outward or superficial