off-speed pitch vs change-of-pace ball

off-speed pitch and change-of-pace ball both are nouns.

Word	Noun	Adjective	Verb	Adverb
off-speed pitch	Yes	No	No	No
change-of-pace ball	Yes	No	No	No

As nouns, off-speed pitch and change-of-pace ball are synonyms defined as:

off-speed pitch and change-of-pace ball: a baseball thrown with little velocity when the batter is expecting a fastball

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

off-speed pitch (noun)	change-of-pace ball (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