arduous vs grueling

arduous and grueling both are adjectives.

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

As adjectives, arduous and grueling are synonyms defined as:

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

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

arduous (adjective)	grueling (adjective)
difficult to accomplish; demanding considerable mental effort and skill	characterized by effort to the point of exhaustion; especially physical effort
characterized by effort to the point of exhaustion; especially physical effort
taxing to the utmost; testing powers of endurance