casual vs nonchalant

casual and nonchalant both are adjectives.

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

As adjectives, casual and nonchalant are synonyms defined as:

Other synonyms of casual include insouciant.

casual (adjective)	nonchalant (adjective)
hasty and without attention to detail; not thorough	marked by blithe unconcern
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