grueling vs backbreaking

grueling and backbreaking both are adjectives.

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

As adjectives, grueling and backbreaking are synonyms defined as:

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

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

grueling (adjective)	backbreaking (adjective)
characterized by effort to the point of exhaustion; especially physical effort	characterized by effort to the point of exhaustion; especially physical effort