pc = power compact
no = normal output florescent
ho = high output florescent
vho = very high output florescent
t5 t8 t12 are florescent bulbs and this is how the size is measured. the number after t equals the number of 8ths of an inch the diameter of the bulb. t8 is an inch wide bulb t5's are smaller and 5/8ths and t12's are an inch and a half wide
mh de = metal halide double ended bulb
mh se = metal halide single ended also called mogul
led = light emitting diode