Found this:
All Lumia devices will get some form of Smart Camera, but some devices (e.g. the Nokia Lumia 520) do have a less powerful camera and so some functionality may be excluded. Similarly, some experiences may be optimised for the lower specification devices (Lumia 520, 620, and 720). No final decisions on what, if any, restrictions will be applied, has yet been made, as the Nokia development team is still working on optimising the app.
Me to all 512 devices have same specs. same screen type same resolution and even same insidewhat hardware restriction !!??