Hi Abhinav,

The following points will clear your query:

• MBA is Master of Business Administartion and PGDM is Post Graduation Diploma in Managament Studies.
• MBA is a degree type course whereas PGDM is diploma.
• MBA is offered by universities or institutes that are affiliated by universitity. PGDM is offered by colleges that are not affiliated by any university.
• MBA is exam-oriented whereas PGDM is industry-oriented. MBA provides you theorotical knowledge whereas PGDM syllabus includes the knowledge which is required in industries. 
• Examination of MBA are controlled by universities and that of PGDM are controlled by institutes.

Hope it helps. All the best!!!