(threadbump) I own a 2014 SR5 and just took delivery of a 2015 SR5 today. I ordered them both from the factory and they were identical orders. Side by side comparison reveals the following:
a) no difference in the back seat recliners (must have been the 3rd row option that threw off the earlier poster)
b) NO sign of that excitement-inducing trail hitch plug. I asked the salesman, and he hasn't seen one on any of them. I searched the vehicle high and low, and no sign of it. Found the uninstalled front plate frame, cargo net, trailer wire adapter, but no sign of that plastic plug. Maybe that's why all those TRDP's are held at port (wouldn't ship a premium vehicle without this most popular new feature).
c) Finally, the only real difference, and one that will rarely show up for folks. I ordered both the 2014 and 2015 with the base entune (sans navigation, topic of several other threads). The 2014 didn't have the shark fin antennae, and the 2015 does. Not sure if it does anything, other than allow me to tell them apart.