I've been looking at plays as part of procrastinating.

I noticed that sometimes, there's literally no difference in the routes run in medium and long passes. So what decides, whether a pass play is medium or long?

As far as I've understood, the QB throws for the end of the reciever's route, so a 15 yard route in a medium and long pass play should be the same, right? And if they both have a RB drag and a TE drag or out or something "short'ish", shouldn't they pretty much be the same?

Or is the designation about the average of the routes run? Or how deep the QB drops (haven't checked that tbh.)

It's definitely the intended length of the routes. All of my "Long Pass" plays have 1 or more receivers running 20+ yards in the diagram. There might be some intermediate or short patterns also happening as dump-offs, but the main route is the 20+ one. I have noticed that the "Assignment Detail" on some plays only lists 15 yd routes when the diagram clearly shows 20.