Saturated Fats - Are fats derived primarily from animal sources such as beef and similar products. These fats are solid at room temperature, such as the fat ring on the outer edge of a nice T-bone or New York strip steak. Saturated fats are the type you generally would like to avoid. They can stick to the walls of your blood vessels and clog your arteries. Saturated fats should be limited to less than 10% of the total calories eaten in a day.

Unsaturated Fats - Generally, unsaturated fats come from plant sources such as canola oil, olive, and similar products. They are liquid at room temperature. They contain the same amount of calories as saturated fat but they do not clog your arteries. Can be further divided into monounsaturated and polyunsaturated fat. It is recommended that you replace saturated fats in your diet with monounsaturated fats whenever possible as these are thought to be generally helpful from a health standpoint.

Additional Resources:

 http://www.americanheart.org/presenter.jhtml?identifier=3045790