Following are the importance of osmosis

1. Osmosis is a means by which plant cells maintain their water content despite the loss of water to the air that constantly occurring.
   
   
2. It helps the absorption of water by roots hairs from the cells.
   
   
3. Cell to cell diffusion of water is also affected by osmosis.
   
   
4. Higher osmosis pressure of cells provides resistance to the plants against drought injury.
   
   
5. It controls the opening and closing of stomata during transpiration through its regulation of the turgidity of guard cells.

Here is the difference between osmosis and diffusion