casual vs occasional

casual and occasional both are adjectives.

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

As adjectives, casual and occasional are synonyms defined as:

casual (adjective)	occasional (adjective)
hasty and without attention to detail; not thorough	occurring from time to time
not showing effort or strain	occurring on a temporary or irregular basis
occurring on a temporary or irregular basis	recurring or reappearing from time to time
marked by blithe unconcern	occurring or appearing at usually irregular intervals
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