undependable vs erratic

undependable and erratic both are adjectives.

Word	Noun	Adjective	Verb	Adverb
undependable	No	Yes	No	No
erratic	No	Yes	No	No

undependable (adjective)	erratic (adjective)
not worthy of reliance or trust	liable to sudden unpredictable change
liable to be erroneous or misleading	likely to perform unpredictably
	having no fixed course