AWS or Annual Wage Supplement is commonly known to employees as the 13th month Bonus that most companies gave out either at the year end or prior to Chinese New Year, thus basically it's the same component.
As for Bonus, there are varying types of bonus that a company can give out like Performance Bonus, Variable Bonus, Profit-sharing Bonus. Different criterias and amount for each type and not all companies give. Lately under recommendations from National Wage Council, a new component is set within the monthly pay known as MVC or Monthly Variable Component, which is actually the Variable Bonus. Instead of been paid out in lumpsum, it's broken up into 12 monthly components and in times that the company doesn't do well and need to have a pay cut, the MVC will ease the load.
mancha
AWS, Annual Wage Supplement a.k.a 13 month bonus, payable to employees who are still with the company on 31 December. Purpose I think is to discourage job hopping. Also to keep the monthly salary low, so that the company can remain competitive. The co is supposed to pay more if it is doing well.
Bonus, whatever name it comes with. Performance Bonus, Variable Bonus, Profit Sharing, is the extra that is declared by the co. Usually from April onwards.