Labor regulations in India are at state-level. Minimum wages, max hours per day, max hours per week/period, duration of breaks, spacing of breaks if overtime is involved, number of consecutive days of work (eg: 7th day must be off, if for some reason the worker must be scheduled for the 7th day, then policies for dayoffs/compensatory offs required), overtime pay rules, hours of operation and what is considered night shift, supervisory requirements (eg: need a night shift woman manager if utilizing women in night shifts), transportation and security requirements and the list goes on.
At some level, the states do compete on setting labor rules policies to appear business-friendly. The article mentions three southern states where Apple's plants are operating. You can be sure that the rules vary in slightly different ways between the states.
Again, the statutory rules are governed by different laws -- eg: Shops and Establishments Act vs. Factories Act. Historically, they have been different. For eg: A software company or contact center might be governed by the former while a manufacturing plant would be governed by the latter.