Efficient or effective?
Many people make mistakes in using the words "efficient" and "effective" correctly. Here's a simple explanation of when you should use "efficient" and "effective" in English:
Being EFFICIENT means working in a well-organized way, without wasting time or energy.
#He made very efficient use of his time in revising for the exam.
#This engine is really efficient, it can run for 30 km on only 1 liter of fuel.
Being EFFECTIVE means working well and producing the results that were intended.
#This medicine is really effective. My headache’s totally gone now!
#The only effective way to avoid allergy attacks at this time of the year is to stay indoors.
You could say that EFFICIENCY describes doing a certain task the right way, whereas EFFECTIVENESS focuses on desired results.