Like software architecture, product management has a variety of definitions. One that I've found useful is as follows :
My own definition is a bit simpler: Product management is the comprehensive set of activities required to create and sustain winning solutions. It is like software architecture in that it is also about "the big picture." In reality, though, the big picture of product management is an even bigger picture than that of software architecture. Product managers deal with everything from pricing the product to creating data sheets, from defining and educating the sales channel to monitoring the behavior of competitors. The job is no less difficult than that of an architect and in some ways is considerably harder.