unpredictable vs occasional

unpredictable and occasional both are adjectives.

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

unpredictable (adjective)	occasional (adjective)
not capable of being foretold	occurring from time to time
unknown in advance	occurring on a temporary or irregular basis
not occurring at a regular rate or fixed intervals	recurring or reappearing from time to time
	occurring or appearing at usually irregular intervals