jump ball vs tap-off

jump ball and tap-off both are nouns.

Word	Noun	Adjective	Verb	Adverb
jump ball	Yes	No	No	No
tap-off	Yes	No	No	No

As nouns, tap-off is a hyponym of jump ball; that is, tap-off is a word with a more specific, narrower meaning than jump ball:

jump ball: (basketball) the way play begins or resumes when possession is disputed; an official tosses the ball up between two players who jump in an effort to tap it to a teammate
tap-off: the act of starting a basketball game with a jump ball

Other hyponyms of jump ball include tip-off.

jump ball (noun)	tap-off (noun)
(basketball) the way play begins or resumes when possession is disputed; an official tosses the ball up between two players who jump in an effort to tap it to a teammate	the act of starting a basketball game with a jump ball