The main difference between the Army Reserves and National Guard is that the NG is funded by whatever your state of residence is and AR is federally funded. 6SPD has a point about going Army full time vs. part time. Gonefhsn is also right with still needing a civillian job to keep going. Just make sure to do your homework on whatever MOS you may be interested in, but know this...whatever MOS you choose, you WILL get deployed sooner or later. And if you've heard about this Try One program for the National Guard, don't believe it. Try One is a theoretical program where people can try it for a year to see if they like it. Well, be mindful of terms like "Stop Loss" and "Involuntary Extension". I found this article about it:
Get as much information you can BEFORE you sign ANYTHING. Trust me when I say Recruiters WILL tell you what you want to hear to get you to sign. When they do, Uncle Sam could keep you longer than you like. Just be prepared for a commitment if you do sign up. Good luck.