What is the difference between the Indian Institute of Management Calcutta (IIM C) and the Post Graduate Programme in Management for executives (PGPX)?

I did not get what you want to know and compare exactly but assuming that you want to compare the MBA or the flagship program offered by IIM C and the PGPX course, as one is a college and the other is a course. 

The top Indian business school IIM C offers a two-year full-time MBA program. The program is for recent graduates or those with five years of work experience. The curriculum teaches management and business practices. While PGPX is a one-year full-time program for executives with at least five years of experience. The program trains experienced managers to lead their companies. The customizable curriculum is targeted at experienced executives.

In conclusion, the flagship program (MBA) of IIM C and PGPX offer management education, but their audiences, duration, and focus differ. PGPX is for experienced executives, while IIM C is for recent grads with little or no work experience.