How much brighter is a supernova compared to a standard nova event across interstellar distances?

A supernova is billions of times brighter than a nova.

The difference in luminosity between a nova and a supernova is immense, reflecting the scale of the physical processes involved. A nova, being a surface thermonuclear flash on a white dwarf, results in a significant but localized brightening. In stark contrast, a supernova represents the catastrophic, total disintegration of a massive star or the runaway detonation of a white dwarf, releasing energy on a colossal scale. This disparity means that a supernova explosion can momentarily outshine entire galaxies, making it billions of times brighter than even a vivid nova, which allows astronomers to detect supernovae even in distant galaxies.