Let us take a step back and walkthrough the definitions as presented earlier in this article.
New Product Development: The process which involves forming strategy, organizing requirements, generating concepts, creating product & marketing plan, evaluating and subsequent commercialization, thereby bringing a new product to the marketplace.
Product development is a complete cycle which starts from market analysis, product specifications to concept/industrial design, costing, scheduling, testing, manufacturing and ends at logistics, customer feedback, improvements and the final act of getting a product into the market.
Industrial Design:The practice of forming concepts and designing products, which are to be manufactured through techniques of mass production.
Product Design is complete process that includes product industrial design, user experience, 3D Cad modeling, design calculations, simulation. Responsibility of a good product design is to make product working as per design specifications. It is safe to say that product industrial design is one of the many stages of NPD. It is a crucial subset of NPD which is necessary for the successful completion of entire development cycle.