Pos v Neg Switched?

I've looked around the internet, and asked some people about this and can't get an answer. What's the difference between positively sitched systems, and negatively switched systems? :confused: Same question regarding grounding. My car is negative and I installed headlight flashers, and required cutting the high-beam wires for both headlights, and my high-beams need to be on for them to work. My friend has a positive system, and he just needed to cut one wire, and doesn't need the highs on for them to flash. Thanks for the help

Anyone? Bueller?