User blog comment:FairyRaven/Fairy Tail Chapter 370: Demons Reincarnated, Review and Commentary/@comment-4999650-20140207124039/@comment-7418318-20140207142839

I wonder if people will ever stop calling any kind of beam "laser".

A laser is light. Jupiter combined Air, Earth, Fire and Water Magic into a magical blast of some kind.

And as far as damage potential goes, comparing a bomb with a directed energy attack (including laser) can make sense if done right. But for that you have to keep in mind that a bomb will spread the damage around (even shaped charges, though to a far lesser degree).

Also we don't know how varied the damage potential of a Jupiter Cannon are. Most likely Jupiter just refers to the method with which the four elements are combined and fired, but that still leaves a lot of room for variations depending on the strength of the magic sources, so 500 times Jupiter is telling us pretty much nothing in the first place.