Efficacy-Efficiency | Commonly Confused Words

Efficacy

/ˈefɪkəsi/

Effectiveness in producing a desired result or success.

/ɪˈfɪʃənsi/

The ability to accomplish a task with the least waste of time and effort

Better Way to Efficiency.There was a great increase in mechanical and agricultural efficiency.Obey the law of forced efficiency.

Efficacy is about whether something works at all, while efficiency is about how well it works with the least effort.
Efficacy is like asking, Does this drug cure the disease?, while efficiency is like asking, Does this drug cure the disease without wasting resources?
Think of a car: efficacy is whether the car can get you from point A to point B, efficiency is about how much fuel it uses to get there.
Efficacy is concerned with the potential result, while efficiency concerns the best operational performance.
Efficacy can often imply a yes or no outcome, whereas efficiency is measured on a scale of better or worse.