infrequent vs occasional

infrequent and occasional both are adjectives.

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

infrequent (adjective)	occasional (adjective)
not frequent; not occurring regularly or at short intervals	occurring from time to time
	occurring on a temporary or irregular basis
	recurring or reappearing from time to time
	occurring or appearing at usually irregular intervals