As it has been said “A Project Manager is like a mid wife- he/she delivers the baby, hands it over to the mother and moves on. The baby being the product and the mother being the Product Manager”
The Project Manager cares for the product up until the product is delivered and then hands the responsibility over to the mother.
Whereas the Product Manager’s role is very similar to that of mother’s role, he conceives the idea, runs with it for months, through gathering information about product requirements, development, testing etc. He goes through the exercise of bringing that product to market and then supports it until it goes obsolete.
One of the key arguments here is to clearly define the difference between project and product management. Product managers are focused on what to build when, and Project managers are focused on how to build it and who is going to develop or provide which parts when.
Project managers are responsible for the successful delivery of a project — a one-time endeavour with a goal, scope, deadline, budget, and other constraints.
A project manager will work to align resources, manage issues and risks, and basically coordinate all of the various elements necessary to complete the project.
As they relate to products, projects can be undertaken to build a product, to add new features to a product, or create new versions or extensions of a product. When the project is complete, the project manager will usually move to a new project, which may be related to a different product.
Product managers are responsible for the overall and ongoing success of a product. Once the project to build the product is complete and the project manager has moved on, the product manager remains to manage the product through the entire life cycle.
Other projects related to the product may be initiated, with the product manager being the one constant stream throughout, defining the project goals and guiding the team to accomplish the business objectives that have been defined.
One challenge of the two roles is that they can appear to be at odds with each other. A product manager may want to add a lot of features to meet observed customer needs, but the project manager may want to keep scope as small as possible so that the project is delivered on time and under budget.