I am a newbie on this topic.
I have been surfing the web looking for information about the topic and, now, I am also more confused. If I am not wrong they manage the hardware and create a connection between the user-space and the real physical part of the device (please correct me if it is not so). But which is the real difference between one and another? How can I classify them? What I am looking for is a clear answer that can drive me on right reference to understand better and study deeply the field.