I thought souffles would be baked, while mousses would be only whipped, but I've seen recipes for cooked mousses before. Is this just a case of using the wrong name for the wrong recipe or are there important differences between them?
There is no strict delineation between these two terms. Either can be savory or sweet.
Some common differences are:
- Mousses may get their foaminess from from plain whipped egg whites, a meringue, whole eggs, whipped cream, or something else; a souffle is always leavened by whipped egg whites.
- Mousses (except for some seafood mousses, which are gently poached) are rarely cooked as a whole dish; souffles are always baked to get additional rise.
- Mousses are almost always served cold; souffles are usually served hot, immediately out of the oven to retain the additional rise they get in the heat of the oven.
One might consider souffles a type of baked mousse, much as quiches are a specific type of tart, but that terminology is rarely used.