will power vs willpower

will power and willpower both are nouns.

Word	Noun	Adjective	Verb	Adverb
will power	Yes	No	No	No
willpower	Yes	No	No	No

As nouns, will power and willpower are synonyms defined as:

will power and willpower: the trait of resolutely controlling your own behavior

Other synonyms of will power include possession, self-command, self-control, self-possession, self-will.

will power (noun)	willpower (noun)
the trait of resolutely controlling your own behavior	the trait of resolutely controlling your own behavior