Most "ballasts" use the same or similar ballast coil.... (as long as you are comparing the same- pule, probe, hqi, etc.). They do differ in the source of the ballast (USA, China, Hungary, etc.) and the housing they mount inside. The typical "commercial" are designed as a heat sink, housing, and luminarc holder. The typical aquatic use is usually a remote mount housing. Hydroponic is usually a commercial housing adaptation.
Look inside at the decal on the ballast itself. (unplug all power first, and do NOT touch any exposed wiring or terminals). That number (M59, etc.) is indication of what type of bulb it is designed to run. Post it here and someone should be able to see exactly what you have.
Rgds, D