As long as the light wattage is the same and the bulb design similar (Omni-Directional, Spot light, etc) you can basically use whatever. It's important because a 75W omni light (no reflector) gives off less focused heat than a spot light. So if you get good results using a 75W bulb in your setup which is an omni model, don't replace it with a 75W spot because it will be way too hot.
Just some examples in case it isn't clear...
omni-directional light:
http://download.p4c.philips.com/lfb/..._en_aa_001.pdf
spot light:
http://download.p4c.philips.com/lfb/..._en_aa_001.pdf
And then even, between different manufacturers there are differences in heat output because that is directly tied to the efficiency of the lamp itself (higher efficiency and less energy is converted to heat instead of light).