The Play Store on your device will show you apps which it thinks are compatible with that device. So if there is an app which is compatible with one device but not the other it will be visible only on that device.
When you look at an app description in the Play Store it will tell you what android versions it is compatible with, but compatibility may also depend on screen resolution, chipset, etc. If you look at an app via the web (play.google.com) it should show you which of your devices it is compatible with.