grueling vs arduous

grueling and arduous both are adjectives.

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

As adjectives, grueling and arduous are synonyms defined as:

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

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

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