Question

What is the difference between effectiveness and efficiency

Answer 1

Effectiveness describes how well a policy or tool does it's job. It measures only the effect of whatever is being done.

Efficiency describes how much is done per unit of input. If say, one policy will reduce the death toll on roads by 50,000 per year at a cost of £50,000 per year, and another policy will reduce the death toll by 25,000 per year at a cost of £5,000 per year - the second policy is more efficient at 5 lives saved per pound spent, but the first policy is more effective as it saves more lives overall.

Answer 2

Effectiveness deals with the outcome. It tells whether goal has been achieved or not.
Efficiciency deals with the cost incurred to achieve that goal.