The first difference is that All-Seeing Eye is not actively preventing actions from taking place in your computer,
Which is why IDS is inferior to IDPS

and how much resource does it eat up?
I was wondering when you would get around to that

I would suggest that you seriously reconsider your choice of Norton. It is a major resource drain and frequently does not play nice with other security software.

Out of curiosity, what exactly is your hardware?