Do you use these terms as synonyms? You are wrong!
Efficiency is scientifically output / input. Efficiency is measured to maximize output with minimum resources. It refers to doing things in right way. Say, you produce 10 kgs of potatoes with 1 kg of fertilizer. To be efficient, you need to produce more potatoes with fertilizer measuring 1 kg or less.
Effectiveness, on the other hand, means doing the right thing. Say, you produce 10 kgs of potatoes with 1 kg of fertilizer. To be effective as a farmer, you need to produce more good potatoes than bad potatoes; you don't have to bother about your fertilizer.