change-up vs change-of-pace

change-up and change-of-pace both are nouns.

Word	Noun	Adjective	Verb	Adverb
change-up	Yes	No	No	No
change-of-pace	Yes	No	No	No

As nouns, change-up and change-of-pace are synonyms defined as:

change-up and change-of-pace: a baseball thrown with little velocity when the batter is expecting a fastball

Other synonyms of change-up include change-of-pace ball, off-speed pitch.

change-up (noun)	change-of-pace (noun)
a baseball thrown with little velocity when the batter is expecting a fastball	a baseball thrown with little velocity when the batter is expecting a fastball