Dear Kashyap,
Good question...
The Factories Act is basically related to three main basics:
Firstly, the health of the employees.
Secondly, the safety of the employees.
Finally, the welfare of the employees.
In relation to overtime (OT) for the laborers and not for managerial staff, there is no clear definition for the same. However, managers can also request overtime pay for the hours they worked. Usually, due to seniority and a better salary structure compared to laborers, executives, officers, managers, etc., do not ask for OT. However, there is no straightforward provision stating that they will not be eligible for OT.
Regarding the difference between the Shops Act and the Factories Act:
The Factories Act is applicable to manufacturing units where 20 or more persons are working on any day in a year and where any kind of manufacturing activities are being performed.
The Shops and Establishments Act is applicable to shops, offices, head offices, corporate offices, etc., where any kind of services are provided and not manufactured. The number of persons working could be any. As per the act, shops must open and close as per the specified times according to the industry.
I hope this information has answered some of your queries.