Question: What is the difference between *make decision* and *take decision*? When to use the one and when the other?

Answer: 
I disagree with other answers that this is simply regional variation, with no difference in meaning. While I'm sure there are regional variations, and certainly the core meaning is the same, to me (native southern UK) the meanings are definitely slightly different:

* The phrase "making a decision" is the more common phrase. It can refer to the actual moment where a course of action is chosen (and just that moment), but also sometimes to the whole process leading up to it (where one might undertake research, have discussions, think and so on, in order to prepare oneself for the decision itself): "The committee took several months to make a decision."
* The phrase "taking a decision", by contrast, only refers to the decisive moment itself, and not to the process leading up to it. It has more formal connotation, and an implication that the decision will have serious consequences, and that the person deciding will be responsible for them; it has a sense of finality about it.

Some examples may help clarify:

* I haven't made a decision about where to go on holiday. (Informal, consequences not serious, nobody's going to hold me to account.)
* The president took the decision to invade Elbonia.
* Bob was fired because he took the decision to outsource the call centre to Mars.
* The decision-making process took a number of weeks: the engineers did the research and made recommendations, but it was the manager who took the final decision.

In support of this position it is worth using Google to search for ["take a decision"](http://www.google.co.uk/#sclient=psy&hl=en&q=site%3anews.bbc.co.uk+%22take+a+decision%22&aq=f&aqi=&aql=&oq=&pbx=1&fp=2fb1b9b17983bff3) and ["make a decision"](http://www.google.co.uk/#sclient=psy&hl=en&q=site%3anews.bbc.co.uk+%22make+a+decision%22&aq=f&aqi=&aql=&oq=&pbx=1&fp=2fb1b9b17983bff3) on the BBC News website. The former are (at time of writing) all about formal decisions (by governments, official bodies, international committees etc); the latter - once quotes from US politicians are filtered out - mostly about personal or informal decisions, and about the decision process rather than any decision being taken:

* "The Arab leaders should take a decision to stop negotiating..."
* "But, as a public consultation into UK future energy needs begins, he said it was time to take a decision on nuclear."
* "I usually sleep on it, relax and then make a decision which is usually the correct decision."
* "It's not to say that if you've got to make a decision you should make it in a fraction of a second - that is daft."
* "When we make a decision, we are supposed to consciously analyse the alternatives and carefully weigh the pros and cons."
making a decision is something you have engineered; taking a decision is something that is put before you (active versus passive).