Pgdm is very much equivalent to Mba but main difference is pgdm is more industry oriented and institutions will change the syllabus according to the current scenario.

Hi, MBA is a degree course offered by the colleges affiliated to the universities so only universities can offer MBA program. Whereas PGDM, these institutes that are recognised by AICTE and which are autonomous and not affiliated to any university. Fees is high in PGDM whereas in MBA there is less fees. It is not necessary both are at same level.
The syllabus can be similar in both the degree/diplomas.
Famous MBA institutes are like FMS-DU, IIFT
Famous PGDM institutes are IIM's, XLRI etc.
Good Luck.