thrower vs twirler

thrower and twirler both are nouns.

Word	Noun	Adjective	Verb	Adverb
thrower	Yes	No	No	No
twirler	Yes	No	No	No

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

thrower: someone who projects something (especially by a rapid motion of the arm)
twirler: (baseball) the person who does the pitching

Other hyponyms of thrower include pelter, hurler, pitcher, slinger, tosser.

thrower (noun)	twirler (noun)
someone who projects something (especially by a rapid motion of the arm)	(baseball) the person who does the pitching
a craftsman who shapes pottery on a potter's wheel and bakes them in a kiln	someone who twirls a baton
a person who twists silk or rayon filaments into a thread or yarn