Dear Vatsalya

The difference between provisional and permanent license is, anybody who has completed his/her MBBS along with the internship (practical training) can apply for permanent registration with MCI; however a candidate who has passed MBBS (qualifying examination) but is desirous of completing the training, i.e. internship in India, and haven't yet completed the internship, he/she can apply for provisional registration. There is a time validity for provisional registration and it will allow you to complete your practical training in India. However, to practice, you will need to have permanent registration and should have completed the training. Given below are the definitions of permanent and provisional registrations as given on official website of NBE. 

“Permanent Registration” means registration for the purpose of enrolment on any State Medical Register or Indian Medical Register after obtaining the Primary Medical qualification followed by completion of such practical training as prescribed either in India or abroad as per the provisions of the Act.

“Provisional Registration” means provisional registration in a State Medical Register or Indian Medical Register for the purpose of undergoing practical training in India as prescribed and for no other purpose by an Indian citizen possessing any primary medical qualification but has not undergone such practical training after obtaining that qualification as may be required by the rules or regulations in force in the country granting the qualification.

Hope it clarifies your query. 

Good Luck!