Regular wedding bands and engagement rings are very different from each other and it is very important to understand what role each piece plays. Tradition is as follows: Wedding bands are the same as wedding rings and are worn by both the groom and the bride. An engagement ring is worn by only the bride. The bride is suppose to wear her wedding band under her engagement ring (closest to her heart). The bride is also able to not wear a wedding band if she chooses not too.
The difference between a wedding band and an engagement ring is quite obvious, according to wisegeek.org, the engagement ring is much more elaborate and extravagant, containing an array of white/colored diamonds, usually with one large diamond in the center. A wedding band that can be worn by both the bride and groom does not traditionally have a large diamond in the center and is much less extravagant. The engagement ring being much more expensive than the wedding band, is presented during the proposal and the wedding bands are exchanged during the wedding ceremony.