Pro is just a distinguishing monicker to imply "in comparison" nowadays. There might be some exclusives to the Pro line, but other than that, the Pro is just a sticker to demand a higher price and cater to a different set of egos. Any iPhone today including the Xr (for similarity of interface, otherwise going down to even an iPhone 7) is "Pro" enough (read: seriously good enough) for a large section of population.
Even the 6s might find arguments in favour of it for many people out there, but let's just say the 7, if not the A11-powered 8 is an adequate baseline for a few more years.
The "Pro" lines just offer a feature extra here and there to differentiate and if there are people that might want it, without even needing it, they will take that Pro iPhone. The rest will be completely happy with their other Pro phones without the Pro monicker. 🤷♂️
iPhone X brought in an OLED display, and now that display is exclusive to the Pro line, if I remember correctly. So.. just marketing. Enjoy your phone and extract its potential to the fullest!