The main differences are the origins and the ingredients.
The high quality traditional German sausages first come from Neu-Isenburg, a small town on the road from Frakfurt to Darmstadt. It is made of prime lean pork and a little salted bacon fat. It is then finely chopped into a smooth paste, put into pork casings and smoked.
The stuff that we call hot dogs are made from very different ingredients and most probably came from America. These ingredients can be anything like pigs' and cows' hearts; and pigs' cheeks. Iced water is added at around 1/3 the weight of the meat and stuffed into Narrow Bullock Runners (casing) and smoked.
Sausages are my favourite! What's yours?