The difference between sugar and artificial sweeteners such as Sweet n' Low and Equal is mainly caloric. Sugar is high calorie and is naturally sweet, while the majority of artificial sweeteners are low calorie or zero-calorie.
Artificial sweeteners are so low calorie because they are mostly made of saccharin, sodium cyclamate or aspartame. While these sugar replacements do contain calories, they are so overly sweet that it takes such a minuscule amount to get the same effect as sugar that few or no calories are present in a standard serving. Saccharin is about 300 to 400 times sweeter than regular cane sugar, but has been banned as a food additive for brief times in Canada and the United States. The other commonly used replacements are sodium cyclamate, which is 30 to 50 times sweeter than sugar, and sucralose, which is 300 to 1000 times sweeter than sugar.
Some artificial sweeteners, such as sucralose, boast that their product has no calories due to the fact that the human body cannot naturally process them. These sweeteners pass through the body without any calories being absorbed. The safety and health effects of artificial sweeteners are a topic of debate all across the world, but they have yet to be proven dangerous when used in moderation.