Effective
Part of speech: adjective
Definition: Having the power to produce an effect or effects. Producing a decided or decisive effect. Efficient, serviceable, or operative. Actually in effect.
Example sentence: Mediation is one of the most effective tools of non-violence. It can turn parties away from conflict, towards compromise.
Efficient
Part of speech: adjective
Definition: Making good, thorough, or careful use of resources; not consuming extra. Especially, making good use of time or energy.Using a particular proportion of available energy.
Example sentence: Like many businessmen of genius he learned that free competition was wasteful, monopoly efficient. And so he simply set about achieving that efficient monopoly.