Dear Friend,
In general the variable pay is entirely is different from the Bonus to be paid under statutory norms. Statutory Bonus is mandatory.
As far as variable pay is concerned, part of your goals / KRAs/ KPIs the organization will pay variable pay ( ie., other than your fixed pay ) on achieving the set targets.This variable pay will be paid on monthly / quarterly/half yearly and annually on achieving the set targets agreed between the employee and the management.
In General there will be a mutually agreed document on variable pay and both ie., Statutory Bonus and variable pay is different, the management can not avoid once it is agreed and documented.
Thanks and regards - kameswarao