Sutra:
70. thEhaththil vyAvrutti thathvasEkaraththil sonnOm.

Meaning:
The difference between the Atma and the body was explained in detail in the rahasya grantha Tatvasekaram by Sri Pillai Lokacharya.

Sri PBA Swami's Sarartha Deepikai:
There are some that argue that the body is the soul or that there is no difference between the soul and the body. Then, how do we show that the soul is different from the body?

Sri Pillai Lokacharya declines to address that issue here. He has already explained that in detail, in another work called Tatvasekaram and he refers to that document here for further study.