ineffective vs inefficient

ineffective and inefficient both are adjectives.

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

As adjectives, ineffective and inefficient are synonyms defined as:

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

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