This mechanism is specie-dependent and stress-dependent.
The antioxidant activity, e.g. involving enzimes of the ascorbate pathway, allows a constant electrons flow in ETC (Electron transport chain) in the chloroplast, protecting against photoinhibition and excitation pressure in the photosystem (mainly PSII).
On the other hand, polyamines act in the protection against structural damage of the photosystem.
They are different, not mutually exclusive and very important mechanism.