If your computer already has bluetooth, I would go for the bluetooh one as it means no additional device needed. If you do not have Bluetooth, I would go with the Microsoft adapter as I find the hardware generally very good and that headset looks nice!
General advice for wireless V bluetooth headsets-
Typically, if I understand you, a Bluetooth VOIP phone would be a simple headset/microphone that connects to a computer and needs a driver / third party software to actually connect to a VOIP provider.
A Wireless VOIP device will simply be straight on to your network without requiring any other computer device. You put the VOIP settings straight into it.
Again, without knowing model numbers or more info, it is hard to tell - I am just talking about a typical Bluetooth headset and a wireless VOIP phone.