grueling vs punishing

grueling and punishing both are adjectives.

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

As adjectives, grueling and punishing are synonyms defined as:

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

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

grueling (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