Hot dogs were originally invented by the Germans--the original name, frankfurters, refers to Frankfurt, Germany, where they were first made. Real, Italian bologna is a very different sausage than what you buy in an Oscar Mayer package, and you would probably not recognize it as bologna. If you go to a real Italian deli, try ordering some, and you'll see what I mean. That said, it's true that lunch-meat bologna, in that familiar O.M. packaging, IS very similar to modern day hot dogs, and does contain most, if not all, the same ingredients as O.M. bologna.
They are similar but not the same thing. They are made from the same ingredients as they are both beef based. However, their recipes are different and it is common to find the bologna as real sausage when it comes to the texture its skin.