Most 3G UMTS operators have been allocated 10Mhz of paired frequency spectrum (i.e. 10MHz uplink+10MHz downlink), typically in the 2100Mhz range allocated worldwide. This is used with two separate paired WCDMA carriers of 5Mhz each. Wideband CDMA differs from the original mobile CDMA system by using fewer, wider frequency range transmissions – CDMA typically uses carriers with a spread of 1.5Mhz.
Apart from the name, this provides benefits in poor or difficult transmission areas (e.g. built up, urban areas). WCDMA also differs by not requiring the basestation transmissions to be phase synchronised with each other (I think this was to get around a Qualcomm patent), making it more complex but in the long term easier to manage.