"effectiveness and efficiency are two sides of same coin." expain along with their definitions.
Efficiencymeans completing the task with minimum possible costs and resources. Efficiency is said to increase if greater benefits are achieved using lesser resources or even if same benefits can be derived by cutting down on resources.
On the other hand,Effectivenessmeans completing the given work in the required time. In other words, it means doing the right things with focus on the end result.
Thus, it can be said that while effectiveness is concerned with just the completion of the task in stipulated time, efficiency is concerned with completion of task but with minimisation of cost and judicious utilisation of resources. Efficiency and Effectiveness are said to be two sides of the same as they must go hand in hand for the accomplishment of organisational goals