What's the difference between a CarPlay-only and a 2-in-1 adapter?

CarPlay-only adapters work exclusively with iPhones, while 2-in-1 adapters add wireless Android Auto support. If your household switches between iPhone and Android phones, a 2-in-1 unit is the safer buy. Android-only adapters (like the AAWireless Two) exist for drivers who don't need CarPlay at all.