slider vs fastball

slider and fastball both are nouns.

Word	Noun	Adjective	Verb	Adverb
slider	Yes	No	No	No
fastball	Yes	No	No	No

As nouns, fastball is a hypernym of slider; that is, fastball is a word with a broader meaning than slider:

slider: a fastball that curves slightly away from the side from which it was thrown
fastball: (baseball) a pitch thrown with maximum velocity

Other hypernyms of slider include bullet, heater, hummer, smoke.

slider (noun)	fastball (noun)
a fastball that curves slightly away from the side from which it was thrown	(baseball) a pitch thrown with maximum velocity
freshwater turtle of United States and South America; frequently raised commercially; some young sold as pets
someone who races the luge
a person who slips or slides because of loss of traction