fax vs telefax

fax is a noun but telefax is not a noun.

Word	Noun	Adjective	Verb	Adverb
fax	Yes	No	Yes	No
telefax	No	No	Yes	No

As verbs, fax and telefax are synonyms defined as:

Other synonyms of fax include facsimile.

fax (noun)	telefax (noun)
duplicator that transmits the copy by wire or radio

fax (verb)	telefax (verb)
send something via a facsimile machine	send something via a facsimile machine