Difference between Diffusion and Osmosis

Diffusion: The movement of particles or molecules from a region of higher concentration to a region of a lower concentration is called diffusion.
or
Random movement of of individual molecules from a region of higher concentration to a region of lower temperature.

Examples: If a bottle filled with some gas or vapours  is opened at a certain place in the room, very soon its molecules become evenly distributed throughout the available space in the room.  Similarly, if a drop of ink is placed in water, it is dissolved and its particles move so that they are evenly distributed throughout the water.
Osmosis: The movement of water molecule through a semipermeable from the region of higher water concentration to the region of less water concentration is called osmosis. The phenomenon of osmosis can be demonstrated by the thistle funnel experiment.

Diffusion vs Osmosis

Diffusion	Osmosis
It is the movement of all types of substances from the area of their higher free energy to the area of their lower free energy.	It is the movement of only solvent or water from its higher free energy or chemical potential to the area of its lower chemical potential when the solute particles are not allowed to diffuse.
Diffusion can operate in ay medium.	Osmosis operates only in a liquid medium.
Diffusion is applicable to all types of substances: solids, liquids or gases.	It is applicable to only solvent part of a solution.
It does not require any semipermeable membrane.	A semipermeable membrane is a must for the operation  of osmosis.
It is purely dependent  upon the free energy of the diffusing substance.	Osmosis is dependent upon the degree of reduction of free energy of one solvent over that of another.
It helps in equalizing the concentration of the diffusing substance throughout the available space.	It does not equalize the concentration of solvent on the two sides of the system.
Turgor pressure or Hydrostatic pressure does not normally operate in diffusion.	Osmosis is opposed by turgor or hydrostatic pressure of system.
It is not influenced by solute potential.	Osmosis is dependent upon the solute potential
Diffusion of a substance is mostly dependent of the presence of other substances	It is dependent upon the number of particles of other substances dissolved in liquid.
Factors like water potential, solute potential and pressure potential do not affect diffusion.	Factors like water potential, solute potential and pressure potential do not affect osmosis in a living system.