inefficient vs ineffective

inefficient and ineffective both are adjectives.

Word	Noun	Adjective	Verb	Adverb
inefficient	No	Yes	No	No
ineffective	No	Yes	No	No

As adjectives, inefficient and ineffective are synonyms defined as:

inefficient and ineffective: lacking the ability or skill to perform effectively; inadequate

inefficient (adjective)	ineffective (adjective)
not producing desired results; wasteful	not producing an intended effect
lacking the ability or skill to perform effectively; inadequate	lacking in power or forcefulness
	lacking the ability or skill to perform effectively; inadequate