left-hander vs lefty

left-hander and lefty both are nouns.

Word	Noun	Adjective	Verb	Adverb
left-hander	Yes	No	No	No
lefty	Yes	No	No	No

As nouns, left-hander and lefty are synonyms defined as:

left-hander and lefty: a person who uses the left hand with greater skill than the right

Other synonyms of left-hander include southpaw.

As nouns, left-hander and lefty are synonyms defined as:

left-hander and lefty: a baseball pitcher who throws the ball with the left hand

Other synonyms of left-hander include left-handed pitcher, left hander, lefthander, southpaw.

left-hander (noun)	lefty (noun)
a person who uses the left hand with greater skill than the right	a person who uses the left hand with greater skill than the right
a baseball pitcher who throws the ball with the left hand	a baseball pitcher who throws the ball with the left hand