Headlight bulbs can be interchangeable to some extent, but it depends on various factors. Different cars may use different types of bulbs such as halogen, LED, or HID bulbs. These bulbs have specific wattage requirements and fitting styles that need to match with the headlight housing and electrical system of the vehicle. It is crucial to check the owner's manual or consult an automotive expert before swapping out headlight bulbs to ensure compatibility and avoid any potential issues.