Final answer:
Gaseous diffusion is the movement of water vapor from a higher to a lower pressure or from the warm to the cool side of a wall, which is distinct from osmosis that specifically involves water crossing a membrane.
Step-by-step explanation:
The diffusion of water vapor through a material from a high pressure to a low pressure or from a warm side of the wall to a cool side is known as gaseous diffusion. This is a type of passive transport where water vapor, along with other gases, tends to move from an area of high concentration to an area of low concentration until equilibrium is achieved. It's crucial to understand that while osmosis refers specifically to the diffusion of water through a selectively permeable membrane due to concentration differences, gaseous diffusion covers a broader range of scenarios, including the movement of water vapor through materials.