What are some points of difference between active and passive transport? Also, what is the difference between diffusion and osmosis?

requires ATP is Water

An active transport occurs against the concentration gradient. The tendency of a substance is to diffuse from the most concentrated compartment to the least. This is why passive transport does not require ATP - it occurs spontaneously. When a substance must be transported against its concentration gradient, it requires energy to activate (active transport). Osmosis is a type of diffusion, being a passive transport. Osmosis specifically refers to water molecules diffusion.