Are 9003 and h4 bulbs the same?

Yes, 9003 and H4 bulbs are functionally identical. The 9003 designation is primarily used in North America, while H4 is the international standard name for the same bulb type. Both are dual-filament halogen bulbs designed to provide both low beam and high beam functions from a single unit within a vehicle's headlight assembly. They are interchangeable.