Hi SaiKrishna,

A Master in Business Administration (MBA) is a degree course offered by the colleges affiliated to the universities. So, only universities can offer MBA programmes. Fees is high in case of PGDM as compared to MBA. MBA institutes charge less fees as it is almost similar to university standard. The course curriculum is rigid, because approvals required from University Curriculum at most Government Universities and Colleges is theoretical, and not frequently updated.

A Post Graduate Diploma in Management (PGDM) is a diploma course offered by the institutes that are recognised by the All India Council for Technical Education (AICTE) and which are autonomous and not affiliated to any university. However, accreditation by Association of Indian Universities (AIU) makes an institute's PGDM course equivalent to an MBA. The course for PGDM is flexible and updated frequently. 

Now to decide which amongst the two is better, depends on what you want to achieve out of your management course.  If your goal is to join the corporate world, then PGDM or MBA makes no difference. What matters is your learning at a B-school. So faculty, curriculum, industry-integration of a B-school is most important. However, if your goal is to get another academic qualification at low cost, MBA fits the requirement well. Again, your MBA budget might be another key factor in deciding whether to opt for MBA or PGDM. PGDM lets you specialize in your areas of interest. 

The best colleges offering PGDM are IIMs, XLRI, MDI etc. The best colleges offering a MBA degree are FMS-Delhi, IITs etc.

Hope this helps. All the best.