Osmosis vs. Diffusion: What's the Difference?
Read the comparison below, or explore it visually. Create a visual lesson comparing osmosis and diffusion using available credits or plan allowance.
Diffusion is the net movement of any particles from a region of higher concentration to lower concentration, while osmosis is the net movement of water across a partially permeable membrane from a dilute solution to a more concentrated one. Osmosis is a special case of diffusion. Both are passive, driven only by the random motion of molecules, and need no energy from the cell.
At a glance
| Osmosis | Diffusion | |
|---|---|---|
| What moves | Water (the solvent) only | Any particles: gases, solutes, liquids |
| Membrane needed | Yes, a partially permeable membrane | No, it happens in open air or liquid |
| Direction | Dilute solution to concentrated solution | High concentration to low concentration |
| Medium | Liquids only | Gases, liquids and even solids, slowly |
| Everyday example | Raisins swelling in a bowl of water | Incense smoke scent filling a room |
Which should you use?
Osmosis explains how water crosses cell membranes, such as root hairs drawing water from soil or raisins swelling in water, and why salted mango pieces release water when making pickle.
Diffusion explains how substances spread down a concentration gradient, such as oxygen moving from lung air sacs into blood, or the scent of an agarbatti filling a room.