How are diffusion and osmosis different?
Osmosis is the diffusion of water molecules. This means that osmosis is a very selective term because it applies only the the movement of water molecules through semi-permeable barriers such as the cell membrane.
Diffusion is a much more general term which can apply to all different types of molecules. For example, when someone sprays perfume and the "scent molecules" gradually spread out in the room so that everyone can smell the perfume - that's diffusion.
Both are examples of passive transport, which means they occur without the input of any additional energy.
Here is a video of a classic experiment to test osmosis in eggs which have had their shells removed.
video from: Noel Pauller