The movement of particles is a vital process and happens in various ways. Osmosis is similar to diffusion but has a couple of differences.
Again you should try to remember this text-book definition.
Osmosis is the diffusion of water through a partial permeable membrane.
A partial permeable membrane is a membrane, barrier, that has holes in it to allow small molecules like water though it. So water, just as in diffusion, goes from high to low.
Osmosis will also happen with solutions that contain other things like sugar. Note that it is still the water that moves.
Concentrated solution – A solution that contains less water
Dilute solution – A solution that contains more water