punchball vs punch bag

punchball and punch bag both are nouns.

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

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

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

Other synonyms of punchball include punching bag, punching ball.

punchball (noun)	punch bag (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