As nouns the difference between inability and inefficiency
is that inability
is lack of the ability to do something; incapability while inefficiency
is lack of efficiency or effectiveness.
lack of the ability to do something; incapability
* 2013 , Daniel Taylor, Jack Wilshere scores twice to ease Arsenal to victory over Marseille'' (in ''The Guardian , 26 November 2013)[http://www.theguardian.com/football/2013/nov/26/arsenal-marseille-match-report-champions-league]
- The Premier League leaders did what many people thought was beyond them in their last European excursion, at the home of Borussia Dortmund, and they made light work of overcoming Marseille on a night when the one-sidedness was not reflected by their inability to add to Jack Wilshere's two goals.
Lack of efficiency or effectiveness.