Creme fraiche is double cream that has been cultured with bacteria to give it a more pungent flavor while double cream is simply a high-fat content heavy cream. Double cream is a term used in Europe to describe what the United States would refer to as heavy whipping cream.
Double cream has 48 percent milk fat, and it is often used as a topping for desserts. Creme fraiche is cultured so it does not have that sweet taste that can be added to double cream. Creme fraiche works well in savory dishes or as a slightly sour cream topping for soups, but some people also enjoy it with sweet treats.