There are two types of Ballasts utilized in lighting fixtures, the electronic and the magnetic ballast. Both types of ballast stabilize the raw electricity into a consistent lighting source, they just go about it in a different way. Magnetic ballasts are made of wire coiled so as to create a magnetic field, while Electronic ballasts use electronic components.
Magnetic ballasts are an older form of technology. They tend to be cheaper than the digital ballasts, but are slightly less efficient because Magnetic Ballasts lose electronic energy in the form of heat as a by product.