[Mit Panchani]"So what i conclude is, camera tracker can be used in place of motion track but not vice vera."
Motion tracking yields a 2D motion path that describes the apparent movement of an object in the 2D comp space.
Camera tracking yields a 3D motion path that translates the motion of the camera from the real world to Ae's 3D space.
Camera tracking is useful as a replacement for motion tracking when the camera moves but the object is static. If both the camera and the object are moving, camera tracking won't give you a good point to use.