The VW (Voice Wide) mode takes up the whole 12.5 Khz bandwidth for voice where the DN (Digital Narrow) mode takes up the 6.25 Khz bandwidth. VW does sound better but as stated does eliminate a few options in DN that some radios offer.
On the FTM-32xx series you cannot select VW mode. You can only select FM or DN. However, if someone calls you in VW and you reply back it will still be heard on both ends.
As a point of correction...DW means Date Wide and is only used by the radio to send text messages, pictures messages, voice messages, or send Fusion telecommands. It is not accessible by the user and is data in the 12.5 Khz bandwidth.