Tempo is derived from Bar|Beat Markers. Groove, or feel, is derived from Sub-Beats—the deviation of subdivisions of the beat from the strict tempo grid determines the groove or feel.
To extract the groove from a selection, set the Detection Resolution to Sub-Beats. This ensures that the inner rhythms within each bar (if they indeed exist) are represented when generating Bar|Beat Markers. These Bar|Beat Markers can then be used to quantize other audio clips or MIDI tracks, thereby conforming to the Bar|Beat Markers generated by Beat Detective.