plywoods have a Laminate or layered configuration. Made of thin layers of wood plies, each placed with grain at 90 (or 45) degrees to its neighbour and stuck together under pressure. Plywood is simply a configuration - it is not a term for cheap wood!
Plywoods for drums are commonly in sheets 1-3mm thick that are pre-laminated commercially. These sheets are then cut to size and made into a ring. With laminate drums there will be at least two and maybe up to 4 or 5 of these rings combined in a pressure mould to make the 6-8mm thick bodhran shell.