What is the difference between an electronic and a magnetic ballast?
Reduced Weight
As you've noticed, electronic ballasts are lighter.
Reduced Lamp Flicker
Because the electronic ballast operates at a higher cycle rate, flicker is less noticeable.
Quieter Operation
Again, because of the high cycle rate, hum is reduced.
More Efficient
Magnetic ballasts can have losses between 5-25%, while electronic ballasts have better current control making them more efficient.
No Starters Required
Magnetic ballasts required a starter to get the lamp lit, electronic ballasts do not require a starter.
Higher Price
Electronic ballasts are typically more expensive, though you may find that this is no longer a problem.