Is a pool spotlight different from a regular outdoor flood light?

yes a pool light is typically a sealed unit. this is to prevent water from entering the light and coming in contact with the electrical components of the light. if water were to enter the light it could damage the light fixture and also trip the light breaker or gfci. in addition in some situations if the light were not installed correctly/electrically protected correctly (with breaker and gfci) could cause a dangerous situation to bathers. to change the light bulb in a pool light fixture the light fixture must be brought above the waters surface and the lense with lense gasket removed bulb changed then lense with lense gasket replaced and the light reinstalled in the light niche in the wall of the pool below the waters surface. you must also use the appropriate bulb for the light fixture.

this is not as simple as just picking up a bulb from Home Depot and threading it in as you would do with an outdoor flood light. light repairs should only be performed by a trained pool professional as it could be dangerous if not done correctly.