Exactly the same steps to replace the whole thing as a bulb. Screw open ring, pull crap out put new crap in done. It literally is unplugging and removing one item either way, only, the full conversion your now done for life never need to worry about it.
Full replacement has cooling built into the housing that goes inside the bucket, the bulb replacement only has little fins on the bulb. Not sure if either is needed or accurate.
If you do bulb only the light shape will be utter garbage, Halogen reflectors don't work right for LEDs.
Having done a full and total led conversion on my whole bike, the worst one was the tail light by far. The bulb didn't fit through the opening in the back of the housing so I had to take it totally apart. Worth the effort though, my lights are bright as hell and the signals are totally invisible when not on.