How are membrane potential different from action potential?

Membrane potential refers to the difference in electric potential across the cell membrane when the cell is at rest. It is created due to the unequal distribution of ions inside and outside the cell and the relative permeability of each intracellular and extracellular ion. The resting membrane potential is typically negative. 

Action potential refers to a specific and rapid sequence of changes in membrane potential that occurs when a neuron sends a signal. It follows a consistent pattern that involves depolarization, repolarization, and a return to the resting membrane potential. When an action potential occurs, there is a transient shift from negative to positive charge, resulting from the flow of sodium ions into the cell and potassium ions out of the cell. Unlike the variable membrane potential, the action potential is an all-or-nothing event with a consistent amplitude and duration once it is triggered.