Pilates is system of exercises involving controlled movement and controlled breathing using a range of apparatuses i.e. props, small weighted balls, foam rollers, large exercise balls, rotating disks, and resistance bands, whereas tradition of yoga involves physical, breathing and mental training and spiritual development as well leading to one’s psycho-physio-physical development. Physical aspect of yoga involves the use of body’s own weight to develop resistance against the muscles which are required to be toned up.
As such, same shape and leanness can also achieved by adopting the physical tradition of yoga, both being isotonic system. So, yoga and pilates are comparable. However, comparison of effects of yoga and pilates relates to the group of muscles which are involved while practicing any set of these two traditions. Obviously, yoga tradition exercises all the muscles.
Yoga has more to do and practice, and achieve in terms of stability and flexibility for body and mind, both. We can compare physical culture of yoga with pilates. But yoga has separate element of pranayama, relaxation, concentration and meditation, which you can practice to get an added advantage.