as far as the tank itself, the only real difference is having corals etc in the tank.
but as far as equipment and water quality there are many differences.
Reef tanks need as near to zero Nitrates as possible. with a FOWLR
if you have a DSB
you should be well on your way to that already. You'll need to keep a closer eye on CA
levels, Alkalinity, Magnesium, Iodine... all important parts to water quality levels for a reef. Corals will also need much stronger lighting than you probably would have for a FOWLR
. And depending on how the FOWLR
is set up, you may need to increase water movement with additional powerheads.