Post Graduation : Product design(NID) Vs Machine design (IIT) ?

i m a Mechanical Engineer and interested in developing and creating new equipments and machines, i would love to working at a place where i would be required to study the problem faced by the user of product and develop solutions accordingly. Where should i try getting admissions into : NID or IIT?

What i m confused about is what actually does product design composes of whether it is about what goes inside the equipment and how it works (technical part) or its more about the aesthetics? as i m not interested in Aesthetics its technical par that excited me. (i read somewhere that product design is about technical part as opposed to industrial design which deals with aesthetics ) i tried exploring it @ NID's site for syllabus so as to get insight what actually student of Product Design does but didn't found any information about it also it didn't had any sample paper for entrance of PG in Product Design.

It would of great help if fellow CEians could provide any information regarding the syllabus or entrance test.
Thanks in advance.