Final answer:
Diffusion is the process where gas molecules disperse throughout a container from higher to lower concentration areas, while effusion is when they escape through a small opening into a vacuum.
Step-by-step explanation:
The process by which gas molecules move quickly and spread out in all directions in response to concentration gradients is called diffusion. In chemistry, this is observed when gas molecules move from an area of higher concentration to an area of lower concentration, leading to an equal distribution throughout a closed container.
Another related process is effusion, where gas molecules escape through a tiny hole into a vacuum; both processes' rates are influenced by the gas's molar mass and are described by Graham's law.