effective vs. efficient

[Hieupt]

Dear English experts,

Would someone advice me the difference between "effective" and "efficient"? To me, sometimes they are replaceable to each other. Is it correct?
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Thank you very much,
Hieu Phan.

P/s: Please just correct if I'm wrong somewhere!

[Alan]

Hi,

'Effective' suggests giving a good effect. We use it as follows: The choice of red in that room is effective because it creates a bright atmosphere. 'Efficient' suggests operating/working well as in: The use of a diesel engine in the car is efficient because it uses less fuel.

Alan
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English as a Second Language
You can read my ESL story Present Simple