The difference between a wet room shower and a walk in shower is that true wet room showers populate a bathroom area with a completely open plan design.
Whilst a wet room shower screen can be used in such a space, the water will flow away via a drain fitted in the floor. In contrast, a walk in shower will usually incorporate one or two glass screens along with a low level shower tray.
For a better insight into all things related to wet room showers, take a look at our blog, Wet Rooms – How To Create The Perfect Showering Space.