What is the difference between strategy and tactics in chess?

As I once read somewhere (I can’t recall where):

Tactics is to do something when there is something to do.

Strategy is to do something when there is nothing to do.

Strategy and tactics concepts stand in chess the same as in war. (Because the chessgame is a war).

In very general terms, strategy is looking for and designing what is the best way, or a good one at least, for trying to arrive first than your opponent to a goal (an exclusive one).

Tactics is the set of ways for the execution of such a plan.

In chess, strategy has a long-term character; and tactics, a short-term character.

It is relatively easy to improve your tactical hability because it is pattern-recognition, and a tactical idea is either good or bad, as a math problem solution.

On the other hand, although I guess strategy is also pattern-recognition, there is also a decision-making component. This implies that you may not be sure or not asset correctly what the consecuences of your decisions are going to be 15 moves ahead.

Note: Originally published here on Quora.