Resolution is just one of many factors that determines your VR experience. In terms of real-world tangible limits resolution imposes on VR development, you're looking at effective viewing distance. The higher the resolution of the screen inside the VR headset, the further into the distance you can resolve. This is because, at a certain distance, you become constrained by the physical size of the pixels on the screen. Higher resolution = smaller pixels = more resolvable detail further into the picture.
But there are other factors that affect the rest of the VR experience - field of view, for example -- how far to the left and right you can see. Also the subpixel spread - the pentile shape of the GearVR screen is to eliminate jailbarring, but it does so at a slightly lower green subpixel resolution (that is offset by the natural higher resolution of the screen in gearVR). You also have to consider the hardware rendering the scene -- lighting is the single most expensive component of a scene when working in VR. As such, GearVR games feature drastically reduced lighting models. While PSVR can't approach even low-end PC VR titles in terms of real-time lighting, it can still perform quite a bit better than a phone with no heatsink on the GPU core. The nature of GearVR's screen being primarily used for a phone also means that the screen doesn't have a custom pixel density tailored to the optics like PSVR does.
PSVR is in a lot of ways a far step beyond GearVR, just not in resolution. Think of it as sort of a midway point between mobile VR and high-end PC VR, edging closer to PCVR than mobile VR.