immaterial vs extraneous

immaterial and extraneous both are adjectives.

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

As adjectives, immaterial and extraneous are synonyms defined as:

immaterial and extraneous: not pertinent to the matter under consideration

Other synonyms of immaterial include impertinent, orthogonal.

immaterial (adjective)	extraneous (adjective)
not consisting of matter	not belonging to that in which it is contained; introduced from an outside source
of no importance or relevance especially to a law case	not pertinent to the matter under consideration
without material form or substance	coming from the outside
not pertinent to the matter under consideration	not essential
(often followed by `to') lacking importance; not mattering one way or the other