I am confused whether to take MBA as course or PGDM? What's the difference between the two? Is PGDM a diploma and not a Degree?

The main reason why postgraduate courses are named as PGDM is because when an Institute is an autonomous body (not affiliated to any university) and conducts management courses, then such Institutes cannot offer MBA degree. Even IIMs, XLRI's doesn't offer MBA degrees; they only give PGP Diploma. I h