Both Samsung NX500 and Samsung NX1 have APS-C sized 28.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another similarity between these two cameras is that both Samsung NX1 and Samsung NX500 sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moire occurring in certain scenes.
Below you can see the NX500 and NX1 sensor size comparison.
Samsung NX500 and Samsung NX1 have sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.