grueling vs gruelling

grueling and gruelling both are adjectives.

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

As adjectives, grueling and gruelling are synonyms defined as:

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

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

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