The operation of all fluorescent lamps is the same. There is energy provided to filaments within the lamps that react with the small amount of mercury that produces ultraviolet energy and then visible light through the phosphors (or Rare Earths). The ballast maintains a consistent power supply to the lamps.
Linear lamps are usually 48” or 96” in length and labeled as “T”. The 48” appears to be more popular due to ease of maintenance. The “T” indicates “Tube”. The number following relates to the diameter of the “Tube”. T12 relates to 12/8” or 1 ½” in diameter. T8 relates to 8/8” or 1” in diameter. All “Tube” sizes will be similar. T5, T3 etc. Compact fluorescent or “biax” lamps work in the same way and are sized in the same way.
T5 HO or high output lamps are working their way into industrial “high bay” installations. There are advantages and dis-advantages with this technology, but if you have a space that is automatically operated with occupancy sensors, then this may be an efficient system that fits your needs.