punching bag vs punchball

punching bag and punchball both are nouns.

Word	Noun	Adjective	Verb	Adverb
punching bag	Yes	No	No	No
punchball	Yes	No	No	No

As nouns, punching bag and punchball are synonyms defined as:

punching bag and punchball: an inflated ball or bag that is suspended and punched for training in boxing

Other synonyms of punching bag include punch bag, punching ball.

punching bag (noun)	punchball (noun)
an inflated ball or bag that is suspended and punched for training in boxing	an inflated ball or bag that is suspended and punched for training in boxing
a person on whom another person vents their anger