Using the same power source - Wearer's movement
Using the same power storage - Mainspring
Using the same power path - Wheel train
The only one difference is the "source of time " and
the control mechanism - Tri-synchro regulator.
This new concept brings us a high accuracy of time display --- ±1sec
Grand Seiko: -3 +5 sec / day
C.O.S.C.: -4 +6 sec / day
Quartz: ±1 sec / day
C.O.S.C. Quartz: ±0.07 sec
Atomic Clock: 0.000000001 sec / day
Therefore, some people say that Spring Drive is a quartz watch.