The Bifold shower door split-folding, inward opening door design is simple and fairly functional. Additionally and because the inner frame has to be slimmer the glass thickness in many models can be varied 4 - 6mm.
The Infold shower door incorporates a special arm mechanism which opens the door into the showering space. Then once you’re in and you close, it very cleverly wraps back around you. Recently prices for this clever design have become more competitive.