A COCKER and an AUTOCOCKER are one and the same thing. a cocker is just an abreviation of the full name
A cocker can be either a mechanical or electro cocker. The names are pretty much self explanatory.
A mechanical cocker, is erm... mechanical, as in the grip frame is not electronic. it has a much longer trigger pull than an electro, and is not capable of anywhere near the rate of fire
They are however really reliable, and a good starter, and a good tourney marker
An electronic cocker (or e-cocker) is a mechanical cocker that has had a storm, e-blade, race elctronic frame fitted to it
allowing it higher rates of fire, paint sensing eyes etc.
Hope that helps.
Dave