the NG is cheaper the biggest being benies. The soldier gets care while active but that is it. No family benies, no veteran benies. Little if any follow up care for injuries and I think combat injuries may be a gray areas. NG has never been used or was intended to be used as they are today. This war and the way this admin has used the military has pretty much destroyed the NG and reserve component. In the future, they will have to have a larger standing army because they will not be able to retain those with any military training.
The NG is suppose to be under the State's Gov (so I am sure they shell out some money) and they get hand me down equipment-after the Army Reserve uses it.
The NG is state, the AR backs up the Army. I went through Basic with some NG. They did the same things but were paid less. It looked like a rip off to me even then.
The much less talked about reason is tha Posse Comitatus doesn't apply to the NG. Lots of legal wrangling there.
Try this site for more info.
http://www.slate.com/id/2112001/