There are only 2 main ways to construct a floor slab - conventional cast-in-situ and the rib and block system.
With a conventional slab, all the components are assembled on site and the entire slab has to be shuttered and all of the concrete poured on site. The advantage is that large spans unsupported can then be achieved with cast-in-situ slabs but are usually much more expensive than alternative systems.
Rib and block systems have the beams and blocks precast and delivered to site. This system uses less concrete and is quicker and cheaper than conventional slabs.