Answer:
An epidemic is the spread of a disease on a local area, a single country, or a few countries at max, while a pandemic is the spread of a disease over a vast area of the world.
This means that the treatment of an epidemic will be similar to the treatment of a pandemic but to a more local scale, without necessarily entailing the coordination of global institutions like the World Health Organization.
A pandemic, on the contrary, will always be treated at a global scale, which means that global coordination is a must in this case.