What is the major difference between saturated and unsaturated fats?

The correct term would be Fatty Acids because it's the Fatty Acids found in fat that are Saturated or Unsaturated. The biggest difference I know to exist between them would be that Saturated Fats consist of SINGLE bond and Unsaturated fats consist of at least 1 DOUBLE bond. Saturated means think in concentration so you can think of it as supper concentrated fat. Saturated fats last longer and it's harder to be remove from or body compared to Unsaturated fats. Unsaturated fats are considered good to eat if you are watching your cholesterol unlike Saturated fats which often lead to heart disease.