What is the difference between meditation and concentration?

This is one of the most common question asked by people regarding meditation. I wrote one post before explaning about meditation but It did not cover the difference between meditation and concentration.

The main difference between meditation and concentration is that there is no thought process in case of meditation whereas when you concentrate on a particular thing, you hold particular thoughts about that thing. For example, if you are concentrating hard on reading something then you are trying your thought process not to deviate anywhere else. You just want to focus on the particular book that you are reading. So, you are having thoughts while concentrating but your thought process is totally surronding the thing you are concentrating upon.

In case of meditation, there are no thoughts at all. You are not thinking about anything in this state. It is wrong if someone's says that I am doing meditation. Meditation is not an act at all. We cannot do meditation. Meditation is an absolute idle state. So, if someone says that I am doing meditation then it still means that person is not in meditative state. It is even wrong if someone says that I do meditation.