I was reading about phase synchronization of coupled oscillator where the oscillators are synchronized by an applied field. Now the coupled oscillators are synchronized. So my question is that what is the difference between synchronization and the resonance process of oscillators?
Synchronization is when two oscillators completely line up in phase and frequency and you can treat them as one big oscillator. Once they are synchronized, no further energy is required to keep them synchronized, assuming we're ignoring friction.
Resonance is when there is something that is adding on to the oscillator at the resonance frequency, which is dependent on the physical conditions of the oscillator. This resonance frequency is where the added energy is completely in sync with the wave, and none of it is cancelled by the wave itself. Whatever is causing resonance will need to continuously add energy to the oscillator, and the oscillator will be increasing in amplitude.