Both of the devices, the OnePlus 9 and the OnePlus 9 Pro, are using the same 65W Power Adapter, Charging Cable, Snapdragon 888 chipset, cooling technology, wireless charging, Fluid Display, Hasselblad cameras, same selfie cameras, and offering the same battery capacity.
What is different?
OnePlus 9 Pro gets faster 50W wireless charging support besides an IP68 rating for dust and water resistance. It comes with second-gen Fluid Display Technology, which can scale between 1Hz to 120Hz.
However, the cameras installed on both of the phones draw the clearest differentiating line between them.