What's the difference between a cake and a sponge?

Apparently the difference (according to Campden BRI) is that a cake uses fat to stabilise the cake whereas sponge uses air. Technically it's a Victoria cake, then. There's only a few "true" sponges; these are the fatless one like flan cases.

Amazing what you find out on training courses for work.

Apologies if you were expecting a joke.