Difference between body, bulk and substrate?
They are the same. And if the FET is deposited within a special implant, that implant called the tub or the well, then the tub and the well have become the same as body or bulk, and the substrate remains the larger structure upon which all the FETs of either polarity (some in wells for that reversed polarity) are implanted, as well as resistors and capacitors and diodes. And the bond-pads. And the special smiley-faces some layout people add.