What are the key differences between graded potential and action potential in terms of their mechanisms and functions?

Graded potentials are small changes in membrane potential that can be either depolarizing or hyperpolarizing, and they occur in response to stimuli. They are localized and can vary in strength. Action potentials, on the other hand, are large, all-or-nothing changes in membrane potential that are triggered when a threshold is reached. They are propagated along the axon and are essential for long-distance communication in neurons.