resolution vs willpower

resolution and willpower both are nouns.

Word	Noun	Adjective	Verb	Adverb
resolution	Yes	No	No	No
willpower	Yes	No	No	No

As nouns, willpower is a hyponym of resolution; that is, willpower is a word with a more specific, narrower meaning than resolution:

resolution (noun)	willpower (noun)
a decision to do something or to behave in a certain manner	the trait of resolutely controlling your own behavior
finding a solution to a problem
the trait of being resolute
analysis into clear-cut components
something settled or resolved; the outcome of decision making
a statement that solves a problem or explains how to solve the problem
a formal expression by a meeting; agreed to by a vote
(music) a dissonant chord is followed by a consonant chord
the subsidence of swelling or other signs of inflammation (especially in a lung)
the ability of a microscope or telescope to measure the angular separation of images that are close together
(computer science) the number of pixels per square inch on a computer-generated display; the greater the resolution, the better the picture