'Effective' means that it does what it is meant to do. 'Efficient' means that it does this while making good use of resources - for example, not wasting time, energy, manpower, fuel or money. A while ago another member came up with a really nice example which I'll quote, once again. Imagine that you clean all the floors in your house with a tiny toothbrush. This is an effective method, in that it will get your floors very clean. But it is obviously not an efficient method, because it will take a very long time, tire you out and wear out a lot of toothbrushes. With thanks to the originator of that illustration.

effective = functional, workable, capable, able to do the job: - His car is effective at getting from point A to point B. - The treatment has been effective in curing her disease. efficient = gets the best results for the money, energy, or time spent: - His hybrid car is very efficient. - LED lights use energy efficiently.

The best way to consider the difference between "efficient" and "effective" is to consider the difference between doing business in the old way and thinking of improved ways. For example, a company physically delivers printout to a satellite location efficiently by optimizing schedules and assignment of personnel, etc. However, a better, more effective, way would be to transmit the data electronically for printout on-site. Thus it is possible to be the most efficient, yet not be the most effective.

effective means it works well - completes the job well. efficient means it completes the job well, for the least use of resources. A hundred people cleaning your car with toothbrushes would be very effective, but not at all efficient. Hope this makes sense!