Dear Divya,
Greetings!!!
Termination is a disciplinary action whereas resignation is a voluntary action.
In my opinion, it is not at all necessary to give notice period for termination because you can/will terminate an employee only when she/he is found guilty of some misdoing. Having said that, if you are giving a notice period in termination, it is not that bad either because you are actually providing an opportunity to the terminated person to improve herself/himself and at the same time giving them some elbow room to manage their life and career.
The number of days of notice period in case of resignation is purely a contractual obligation between employer and employee.