In software, projects and products are not the same. Projects have a defined end, whereas products are living things with a potentially endless lifespan.

Projects always have an end

Projects have a defined budget, timeline, and scope. Projects are finite. Your job with a project is to achieve the maximum output within the constraints of time & money. Project managers are measured by how well they manage these resources.

Products have a lifespan

Products have a lifespan and act as a living thing. The better nourishment it receives, and the better environment it lives in, the longer it will stay alive to add value. Products are either growing or they are dying. Product managers are measured by how well they can use their resources to increase the product's lifespan, reach, value, and effectiveness.

Projects and Products are complementary.

A software project can be to launch a software product. A rebuild of an existing product could be a project. Great products are continuously iterated on and often maintained by great product managers. Product managers should take the long-term outlook on how to increase the lifespan and utility of the products they are responsible for.

Are you working on a product or a project?

Most companies are used to paying for projects and like the finite nature of the investment. Companies are used to constructing buildings where once it is complete, they don't have to keep spending until it starts to wear out. Software products don't typically start providing a return on investment until they have been iterated on to maximize the value they can return.

Hopefully recognizing the differences between products and projects can help you understand software just a little bit better.