Osmosis only talks about water molecules
Diffusion talks everything other then the water molecules.
So,
Osmosis : water molecules travel from a region of a higher water potential to a region of lower water potential through a partially permeable membrane via osmosis
Diffusion : Travels from a region of higher concentration to a region of lower concentration through a partially permeable membrane via diffusion
The tissue you are referring to here is the xylem, a <u>vascular tissue</u>, whose basic function is to transport water and nutrients from the roots to the rest of the plant.
domain bacteria; kingdom eubacteria
