I have a couple of 5-string banjos. A six string banjo tuned like a guitar won't have that "banjo sound" because part of what gives a banjo that distinctive sound is the way it's tuned, and that "little half string."
The "little half string" on a 5-string banjo, which is the kind of banjo used for bluegrass, is the highest pitched string on the thing, and it is situated where the lowest string would be on a guitar. Typically, you have 3 finger picks, usually a plastic one that goes on the thumb, and usually two metal ones that go on the index and middle fingers. (however, they do make plastic finger picks, and metal thumb picks. Most people happen to prefer a plastic thumb pick and metal finger picks though.) That "little half string" is usually played with the thumb almost every other note or maybe every third note, open, unfretted, so it ends up being a pedal tone a lot, which is why a 6 string banjo tuned like a guitar won't sound right, because that pedal tone will not be natural to duplicate.
A 5 string banjo is typically tuned in open G.
A good book for learning some bluegrass tunes is this one:
Earl Scruggs and the 5-string banjo
BTW, the tape that comes with it is hilarious. He keeps talking about how your "fangers" might cramp up. Hmm, on further review, it appears the book amazon is selling no longer has the tape with it. Bummer. Still a good book, and I don' think the tape really helps all that much, unless you've never even heard a banjo played before.