Reply by Allan Gabston-Howell: I will make the observation that, where a fluorescent lamp generates ultraviolet light through the excitation of the mercury vapor in the glass envelope; white emitting LEDs do not directly emit white light. All of the white/off-white emitting LEDs (as well as many LEDs used to emit amber light for automotive uses) that I have used are an ultraviolet emitting LED which has the top surface of the PN junction die coated with a phosphor (very similar, if not identical, to that used in fluorescent lamps) which emits the desired combination of light frequencies,, in response to being illuminated by the ultraviolet light generated by the LED PN junction.
Irrespective of the proposition of a “drop-in replacement’ of one technology for the other,, both technologies produce the desired light output in a final similar step in the process of light production, while having very different underlying methods of generating the ultraviolet light to begin with.