VBFOOL:
There are many differences between all three styles of playing, most have already been listed prior to my post.
As said before, their names come from the amount of hitters, and the amount of setters. In a 5-1 you have five hitters on the court, one is always setting. A 6-2 has six hitters, two double as setters from the back row. A 4-2 is a simplified 6-2, were the setters are in the front row, and you always have two front row hitters.
That being said, I’d like to clear up one thing. In my previous paragraph, “hitters” means exactly that – people who will be swinging at the ball. One thing I’ve found VERY frustrating is that in a 6-2, you can never dump (above the plane of the net) as the setter. This can make it easy for the other team, because you’re a dead set – they’d be fools to jump with you. A 5-1, you may loose a hitter in the front row – but they must stay true to the setter, or you can squeeze some points past.
5-1’s are the most common offense that I’ve seen run at higher levels of volleyball. In open gyms – 6-2’s and 4-2’s are common for the not so organized teams. I’m not knocking them, I’ve run them and won – it’s just what you team would like to do. A 5-1 is by far one of the best to run, for reasons mrwabam had stated. Your hitters only have to get used to one setter, not two. This may sound like nothing big – but it can play a big part in games. If you have a competent setter, use this style, it will allow for maximum efficiency of your offense. This style also allows your setter to dump, which can help keep the defense true – giving the setter a better chance for one on one block (especially if they jump set). My last reason for loving this style is placement of hitters. If your opposite is a strong hitter, and you have a good middle – they should NEVER be double blocked. A consistent middle should be drawing the blocker every time. A set to the outside may be too slow, and the middle would have time to recover for this play. However a quick set of the opposite should have the middle drawn, and the outside caught off guard often. This leaves a nice big hole for that opposite to swing away – this is a good bread and butter play.
6-2’s are nice… Everyone gets to hit, so that’s not bad. It can be tough though – trapped balls at the net make it hard for the setter to pull them back. This is especially bad since the setter won’t be able to do anything but soft block the ball. The hitters will have to adjust to both setters, and hope they are both having a good game. An advantage of this style of playing is that you can sub out your setters without doing harm. When the setter rotates to the front, you can sub in your big guy for the (often shorter) setter, and let him swing away. This is the main advantage to the 6-2, increasing your block and hitting, while only sacrificing a little bit of your setting.
4-2’s do work, but are usually not taken seriously. This being said – I’ve played in them, and we’ve made them work well and won with them. This gives younger/confused/easily distracted players their JOB, and nothing else. The back row will always be defense, no worrying about moving around. There are two hitters, and one setter – they know their jobs. This doesn’t mean the other ones have a lack of defense… They are just more “confusing” to other players, and have the ability to lack on defense if executed incorrectly. A 4-2 is nice in the aspect that you can play around with your offense. The setter can always dump – and with two hitters you can run a variation of plays. This is my least favorite, but it works – and it works well when applied correctly.
One thing I’d like to touch upon. None of these styles should be leaving two people in the back row EXCEPT for during free balls. During hits and what not the setter should be a defensive player first, setter second. Free balls the setter should be leaving the back row – but heck it’s called a free ball for a reason!
Hope that answers your question - I'll draw up some diagrams tonight, and show you some of what I was talking about.