Efficiency is the often measurable ability to avoid making mistakes or wasting materials, energy, efforts, money, and time while performing a task.
In general, efficiency is a measurable concept, quantitatively determined by the ratio of useful output to total useful input.
Effectiveness is the simpler concept of being able to achieve a desired result, which can be expressed quantitatively but does not usually require more complicated mathematics than addition.
This makes it clear that effectiveness, for example large production numbers, can also be achieved through inefficient processes if, for example, workers are willing or used to working longer hours or with greater physical effort than in other companies or countries or if they can be forced to do so.
Similarly, a company can achieve effectiveness, for example large production numbers, through inefficient processes if it can afford to use more energy per product, for example if energy prices or labor costs or both are lower than for its competitors.