Full moon
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The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon. This means that the lunar hemisphere facing Earth—the near side—is completely sunlit and appears as an approximately circular disk. The full moon occurs roughly once a month.
A full moon rising, seen through the Belt of Venus
A harvest moon. Its orange color is due to greater Rayleigh scattering as the Moon appears close above the horizon, rather than being unique to harvest moons.
Supermoon
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A supermoon is a full moon or a new moon that nearly coincides with perigee—the closest that the Moon comes to the Earth in its elliptic orbit—resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. The technical name is a perigee syzygy or a full Moon around perigee. Because the term supermoon is astrological in origin, it has no precise astronomical definition.
A juxtaposition of the apparent diameters of a more-average full moon on December 20, 2010 (left), and of the supermoon of March 19, 2011 (right) as viewed from Earth.
NASA image showing comparison of a supermoon (left) and a micromoon (right)
The supermoon of March 19, 2011 (right), compared to an average full moon of January 18, 2011 (left), as viewed from Earth