Regulated mods, perhaps unsurprisingly, are made with stricter regulations. There are rules about current, power flow, control features, overheating and automatic cut-offs if it short circuits or encounters other problems. This is obviously safer, and will particularly suit consumers who are unfamiliar with vaping or electronics.
If a customer wants more adaptability and really knows their stuff, you may decide to recommend an unregulated mod that they can play about with themselves. All they will get is the battery, coil and plenty of power.