First, it is most often eaten as a quick and inexpensive snack, not as a full meal. You usually get it from a street stand. Insofar, there is a parallel with hot dogs.
The taste is different, however.
The sausage is a bratwurst, not a frankfurter. It is seared or grilled, so it has a neat crust. The sauce is based on ketchup, but it is more flavourful, because it has curry powder in it or at least curry powder sprinkled on top. The better versions of Currywurst are served with warm sauce. Sometimes, you can get Currywurst which is spiced up with hot chili.
Typical way to eat Currywurst
One of the most popular Currywurst stands in Berlin
Currywurst with french fries and mayonnaise
American hot dogs (usually Danish style) are also known in Germany, but not as popular as Currywurst. Hot dogs are messy to eat and they are considered rather bland in comparison to Currywurst which is a warming comfort food.
