Yes, oatmeal and porridge are the same thing.
The generally accepted idea is that oats are a slower acting carb because they take a longer time to digest and release their sugars into the bloodstream.
Unfortunately, for many of us who have blood glucose meters, we find that this is simply not true.
That is why you will find so many people on her suggesting that we carb count, and test our blood glucose, and make sure that we know exactly what eat type of food does to us. There are some people who find that oats don't raise their blood glucose too high, and some people who find it is as bad as white bread or sweet fruit and white rice. Always good to know what our body is up to!