Deflection of two way slabs is entirely different from one way slab or beams. Due to typical boundary conditions the deflection is less than the case of one way slab which deflect in cylindrical form then the two way slabs which will deform like a saucer/pyramid. The deflection in practice has to be calculated keeping in mind aspect ratio, reinforcement ratio, characteristic stress of steel and concrete, depth of slab versus cover ratio for a particular boundary conditions of the slab. As such the deflection will be different for different boundary conditions of the slab.