In this paper, we investigate the synchronization phenomenon between two Spin-transfer Torque Nanooscillators (STNOs) of different frequencies in two pillar systems under vortex configuration detunings or driving frequencies. The oscillators’ mutual synchronization occurs through magnetic dipolar interaction. Our micromagnetic simulations show that an amplitude fluctuation referred to as [Formula: see text] has a significant impact on determining the synchronization frequency. The evolution of frequency and amplitude fluctuation rate in two different oscillator sizes versus external perpendicular field will be compared and discussed. Our results reveal that the oscillator with lower [Formula: see text], referred to as the “Leader” oscillator, leads the synchronization process. As such, the “follower” oscillator adjusts its frequency as to that of the “Leader”, thus achieving synchronization. We believe that taking [Formula: see text] into consideration can help in controlling synchronization frequencies in future building blocks of any network multi-array spintronics’ devices.