Margarine has less fat than butter.
Blame this one on slick marketing. A teaspoon of butter and stick margarine have exactly the same amounts of fat (4 grams) and calories (35). The only difference is the kind of unhealthy fat: butter has saturated fat, the main cause of high cholesterol. Margarine contains trans fat, which is so insanely unhealthy.
Butter or margarine?
For baking and cooking, switch to soft tub or liquid margarine; many are now trans fat-free and reasonably low in saturated fat. For toast, use soft spreads or, even better, dip your bread into a little extra-virgin olive oil, one of the healthiest fats nature ever invented.