Bluetooth uses a frequency hopping technology to avoid interference from other devices operating in the same frequency. Wibree does not use frequency hopping.

Bluetooth uses fixed packet length. This increases power usage as unnecessary transmission occurs. Wibree has a variable packet length and transmits only when necessary.

Bluetooth drains your cellphone battery as it needs quite a lot of power to remain active. Wibree aims to survive for a full year on a button sized battery.
In contrast to bluetooth, wibree goes into sleep mode when not transmitting. In sleep mode the radio will be off and will save a lot of power. Wibree devices wake up only when they want to transmit.

The major usage difference between wibree and bluetooth is the traffic characteristics. Bluetooth is useful when transferring files, using the handsfree etc where the volume of data that needs to to transfered is considerable.

Wibree is used in areas where only short bursts of data needs to be transmitted. Remotes, sensor data etc.