There is really a difference between PGDM and MBA.
1. MBA is a degree course, while
PGDM is a diploma course.
2. MBA degree is provided by only those institutes that are affiliated to any university.
Eg . JBIMS and FMS, PUMBA. These B-schools are university depts of their respective university.
they follow an academic curriculum as prescribed by the university.
hence these B-Schools give MBA and MMS degrees.
(Note: MMS degrees are the same as MBA degree, the only thing is that Mumbai University gives MMS degrees instead of an MBA.)
3. PGDM courses are offered by private B-Schools that are not affiliated to any University.
eg. IIM’s, XLRI, IIFT, SP Jain.
These institutes prepare their own syllabus, and they are no way dependent on the universities and enjoy full autonomy of their courses.
So B-schools like NMIMS, SP Jain used to provide MMS degrees while they were affiliated to Mumbai University, but now since they have become autonomous , they no longer provide MMS degrees and give PGDM.
And as far as the reputation of these courses are concerned, it all depends on the name of the B-School.