That's like asking for the Encyclopedia Britannica to be summarized in a few short words! Go check out www.campyonly.com, Brankford Bike and www.campagnolo.com.

Generally, in the road gruppos, Record is the lightest and most expensive, Chorus is next and on down. Campy has them in order on their website. Depending on just how high a cool factor you want to pay for, Chorus is a gorgeous, light group that you can get with a triple crank. It will get you plenty of ogling on the road without the expenses of Record. I have it on a Litespeed Tuscany and always get comments.