So you got a cheap scanner, does it give you the same results?
The simple answer is no as the OBD scanner will only show any errors related to emission laws. So yes you will only be able to scan the engine side of a vehicle generally speaking and non of the other computers inside the vehicle.
So yes a normal scan unit will give you more error codes even the ones not related to emissions. Secondly a lot of computer inside a vehicle are linked and any mechanic one would have to scan the complete vehicle which includes all the systems installed.
So for half price you are getting half a vehicle scanner. Remember this when you gloat over a real low cost bargain you just acquired.