Heavy cream, also called heavy whipping cream, is whipping cream with a milk fat content of between 36 and 40 percent. Whipping cream will double in volume when whipped. Heavy cream is not the same as the British double cream.
Double cream has a high fat content which makes it very good for whipping. However it is difficult to find outside the UK and it is possible in most cases to use whipping cream (in the US heavy cream) as an alternative. You always use the same amount of cream if substituting whipping cream.