Why buy an android headunit when a tablet can do the same thing? or what is the difference between the two.
A tablet is android device with its own battery. Perfectly acceptable for playing music over bluetooth or browsing the web, it can even do google maps.
The Android Headunit also runs android but has an overseeing MCU to interface with things like the reversing camera (backup cam). The android doesn’t touch the reversing camera, that is pure MCU which the tablet lacks.
You also get a half decent amplifier that is designed to run car speakers. One of the main uses of an android headunit it to play music through the speakers. A tablet lacks the power amplifier stage of an android headunit.
The android headunit uses the 12v supply of the vehicle to run the MCU, android processor and the amplifier.
Custom fit android headunits also have CAN BUS connectivity to interface with the car A/C or other onboard systems. The universal android headunits do not have the CAN BUS add-on module.
In the Tablet vs Android Headunit question, the main difference is that a headunit has the overseeing MCU that the tablet lacks, along with an automotive grade amplifier for running the car speakers.
Can you use a tablet in a car?
Of course. They are great for google maps and you can even bluetooth to the factory stereo for music. Just check out this neat cup holder mounted tablet cradle on eBay.