What is the difference between PAR30 and PAR38 bulbs?
The number that follows 'PAR' refers to the diameter of the bulb that is 1/8 of an inch (ex: 30/8 = 3.75 inches). So the larger the number the bigger the bulb will be. A PAR 38 can replace a 100 watt PAR38 and PAR30 can replace 75 watt PAR30.