Should I prefer ACM in NICMAR Pune over M.tech in some college like Thapar?

The PGP ACM is a construction management course. It is a mix of Core construction, Project management, General Management, Research Management, and Allied subjects. 

• The course curriculum has been designed for those who are intending to work in execution, planning, and other similar profiles. 
• The graduated from ACM usually works in mid-level management at Contractual firms such as L&T, HCC, Spcl, etc.
• An M.Tech program is usually based on in-depth subjects in the core specialized area. 
• It will equip you in fields of research and technical subjects. You will usually work in a technical, research, or teaching role in your career.

You must choose the path that will suit your core competencies and interests. Any difference in the monetary package would only be evident at the initial stages of a career. You would do equally well with 9-10 work experience in either field, thus it is important to decide based on the interest.