Essentially the same as Gunite, Shotcrete is the ‘wet mix’ – concrete premixed with water, typically ready-mix, that is shot through a nozzle using compressed air that blasts the concrete mix into place on the walls of the pool.
Gunite is different mostly in that the water is added after the concrete dry mix exits the nozzle.
The advantages of Shotcrete (or wet mix) is that there is less waste material that rebounds from the surface (it sticks easier due to all the mix being wet) which keeps the amount of dust right down, and that a greater volume can be applied in the same time, so it can be faster for large surface areas.
In essence, though, one of the main reasons for the name Shotcrete is to avoid trademark infringement on the name Gunite, which is now a trademark of the Allentown corporation. Some other names include pneumatic concrete and guncrete.