elective vs facultative

elective is a noun but facultative is not a noun.

Word	Noun	Adjective	Verb	Adverb
elective	Yes	Yes	No	No
facultative	No	Yes	No	No

As adjectives, elective and facultative are synonyms defined as:

elective (noun)	facultative (noun)
a course that the student can select from among alternatives

elective (adjective)	facultative (adjective)
subject to popular election	able to exist under more than one set of conditions
optional	of or relating to the mental faculties
	granting a privilege or permission or power to do or not do something
	optional