Since this old thread is still active, I'll ask my question here.

I've diligently googled and just can't sort out one piece of information.

I'll be arriving in DUS in the mid-evening and need to get to Koln Rudolfplatz. Since I'd rather get there ASAP after a long flight I'd hate to miss on option while taking time to purchase the ticket, I've downloaded the KVB app and find there are many options every few minutes.

When you enter the information the app gives you many individual route/time options from which you can choose a ticket to purchase. By doing so, are you actually committing yourself to that particular ticket/route or is it actually valid on any upcoming train (within a window of time?) except the ICE? Is the app going to actually produce a route specific ticket, or will it just say DUS-Koln Rudolfplatz. All the options I've checked have the same EU10.71 fare.