casual vs effortless

casual and effortless both are adjectives.

Word	Noun	Adjective	Verb	Adverb
casual	No	Yes	No	No
effortless	No	Yes	No	No

As adjectives, casual and effortless are synonyms defined as:

casual (adjective)	effortless (adjective)
hasty and without attention to detail; not thorough	requiring or apparently requiring no effort
not showing effort or strain	not showing effort or strain
occurring on a temporary or irregular basis
marked by blithe unconcern
appropriate for ordinary or routine occasions
occurring or appearing or singled out by chance
natural and unstudied
characterized by a feeling of irresponsibility
without or seeming to be without plan or method; offhand