backbreaking vs punishing

backbreaking and punishing both are adjectives.

Word	Noun	Adjective	Verb	Adverb
backbreaking	No	Yes	No	No
punishing	No	Yes	No	No

As adjectives, backbreaking and punishing are synonyms defined as:

backbreaking and punishing: characterized by effort to the point of exhaustion; especially physical effort

Other synonyms of backbreaking include arduous, grueling, gruelling, hard, heavy, laborious, operose, toilsome.

backbreaking (adjective)	punishing (adjective)
characterized by effort to the point of exhaustion; especially physical effort	resulting in punishment
	characterized by effort to the point of exhaustion; especially physical effort