What are the differences between autocad electrical and autocad regular?

I have to work with furnace controls, which include both electrical and electronics components of course. The thing is: I am still new to autocad. I have a copy of the Autodesk autocad 2010 regular software. Do I need the Autocad electrical s/w for control circuits? Kindly mention the key differences between the two softwares. Is there any way to compensate for the features of Autocad Electrical that are missing in the regular version, which would mean I wouldn't have to acquire the Electrical s/w. Thank you.