Purposes of these Acts are different. Shops and Establishments Act aims to regulate working hours, welfare of employees, security measures, health and other basic requirements of employees employed in an establishment. This Act does not deal with how to settle disputes between or among employees and employer and employee(s). The Industrial Disputes Act, however, provides for different machinery for settlement of disputes, procedures to be followed in connection with dispute settlement and laying off and closing down of establishments, procedure for retrenchment of employees and so on. Factory covered under Factories Act or establishment covered by Shops and Establishments Act will have to follow ID Act only to find remedies for lay off, closure, termination of workmen etc.
As far as IT sector is concerned, I do not think that it is exempted from the operation of provisions of ID Act. If the establishments in IT firm employs workmen and if they work for profit, they are suppose to follow labour laws also. Certainly, certain concessions are offered to them. But these concessions are for the benefit of the economy and for giving employment opportunities to Indians and not to deter any right of employee nor to drain capital of India.
Regards,
Madhu.T.K