Economical means using money or resources carefully. Economic most often means related to the economy or related to the way goods and services are produced, distributed or consumed, but it can also be used to mean economical. In general, you can almost always use economic, but you should not use economical when you are talking about business studies or the about a nation's economy. Economical tends to be used more often when talking about a bargain or about the choices one makes for a household budget. Hope that helps.

economic = relating to money economical = saving money, putting money to good use - The economic conditions in Jordan are favorable for investment. - In the long term, a Japanese car is more economical than a German car. I'm not aware of any way to use "economic" to mean "economical" or vice versa.