Urgent Help in Modelling

Hello everyone,
I hv created 3D mouse but in render bottom of the mouse seems to be different from the one on viewport.I am a newbie in blender. Pleeeeeeeees reply soon, badly need ur help.


Thanks in Advance

For the bottom object you have smooth shading set and it is trying to smooth the normals between the side and base faces which is at a sharp angle.
For the bottom object add and Edge Split modifier and or Subdivision Surface modifier

You should also give both objects a material