Traditionally, fluorescent lighting was used for seedlings, cuttings and plants with low light-level requirements and HID was used for established plants and plants with higher light-level requirements. Advances in fluorescent lighting technology, however, have provided more options for horticulturists.  T5 fluorescent’s high-light output combined with its low heat and energy consumption makes it an ideal light source to grow a broader array of plants.  Usually, these types of lights are used for seedlings, clones, and some leafy greens where the light can be positioned close to the plants.
Frequency output to the lamp and energy conversion from electricity to usable light are the biggest differences between magnetic HID ballasts and electronic ballasts. Magnetic ballasts produce a frequency of 60 Hz. Electronic ballasts vary from manufacturer to manufacturer, but the frequency produced can be 400x that of an magnetic ballast. Magnetic ballasts produce more heat than electronic ballasts, thus making electronic ballasts more efficient at converting electricity into usable light. You will not, however, save money on your electric bill by using electronic ballasts. Since your power bill is based on kilowatt-hours and not efficiency, a 1000 watt electronic ballast will cost you about the same as a 1000 watt magnetic ballast to operate.