gruelling vs grueling

gruelling and grueling both are adjectives.

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

As adjectives, gruelling and grueling are synonyms defined as:

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

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

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