What is different about a pool specific light bulb?

[Who?]

New pool owner here. Pool light bulb is burned out. It was a 500W 120V incandescent. Before I go buy new bulb I was wondering what makes a bulb with "pool and spa" written on it different? It visually appears pretty standard. Could I swap in an outdoor halogen flood lamp that I have lying around? I suspect the answer is no, but curiosity has me asking this question. Thanks!

 

[chiefwej]

I’m surprised you have 500watt floodlight bulbs just “lying around”. They just aren’t very common. If you want to replace it with something else, here is what I used. LED floodlight only 55watt draw and extremely bright, and it is designed for use in a pool fixture.i can’t speak as to its longevity, since I’ve only had it in place for a month or so. When you replace a pool bulb, be sure to use a new gasket.

https://www.amazon.com/dp/B071G135QN/?coliid=I3I7WEB10ACO1J&colid=3FNCU5YI2QIX2&psc=0&ref_=lv_ov_lig_dp_it