Root pressure comes from osmotic value and turgor pressure comes from the cell walls
A plant can make water enter its roots when the soil is not really saturated with water. The water would normally not enter the root in quantities that are useful for the plant.
The plant solves this by concentrating solubles in the roots, which causes its osmotic value to rise.
This increased osmotic value causes the osmotic pressure to increase, after which water will start entering the roots.
Turgor pressure is something different. Turgor pressure is caused by the cell wall. The cell swells when it takes in water. This water increases the cellular volume, until it reaches the wall. The wall will push it back and it ensures that no more water can enter the cell