Question: what is the difference between a sponge and a cake?
Answer: What is the difference between "a cake" and "a sponge"? ... A Sponge is basically the foundation on which cake is built. The sponge can be plain sponge (e.g. a pound cake) or plain sponge pre-prepared to take on icing, fondant, frosting, chocolate-ganache, etc. that'll turn into cake (or Gateau, in French).