Cook and serve pudding and instant pudding are similar but not the same.
The difference between cook and serve pudding and instant pudding is in how it's made and prepared.
With instant pudding all you have to do is add some milk and stir it up to make instant pudding and do not need a stove to heat the pudding up.
When you're making cook and serve pudding you add the milk and then you have to use a stove to heat the cook and serve pudding.
With cook and serve pudding if you do not use the heat to make the cook and serve pudding then it will not turn out properly.
With the instant pudding it's much easier to make because you don't need any heat or a stove to make it as you can just make the instant pudding using milk and the pudding mix in a bowl and then it will be ready to eat or serve.
The ingredients in both cook and serve pudding and instant pudding are the same but it's just made and prepared different.