Efficient or effective?/ A wizard in something

I am quite confused about when to use "efficient" and "effective". I would greatly appreciate your explanation.

Komsun Wiroonpranee

In terms of usefulness, the one thing in common between the two words is that they describe a person or machine or something that works well and produces the intended results. But what makes the words different is the fact that something efficient does the job well without wasting time or resources.

You need to find effective ways to prevent your staff from disappearing from work during office hours, or you yourself will be in trouble.

This air-conditioner works very efficiently; it reduces my electrical bill by half.

Another meaning of "effective" does not, however, have a similar connotation to "efficient", as you can see in the following explanation. The word "effective" describes something that is so impressive that it grabs the people's attention.

The captain took such an effective penalty kick that the crowd went wild.

When a law or agreement becomes effective, it begins to apply or be valid; we also say it takes effect.

This agreement will be effective from the beginning of the month.

And last but not least, the word "effective" refers to a state of having a particular role in practice, although not officially.

The board is still recruiting a new director, but for now Miss Kathy has assumed effective control of the department.

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Dear Dr English

Is it a compliment or a criticism to call somebody a wizard? Please explain.

Somtawin Wiwatchan

A wizard is a man who has magical powers and uses them to help or to harm people, so there are good wizards as well as bad wizards - as you may know from the Harry Potter series.

But if someone is described as being a wizard in something - such as a computer wizard or financial wizard - they are an expert in that field. It is a compliment.

Einstein was the greatest mathematics wizard of his time.