Product hierarchy classifies products into essential components from basic needs to specific items. It progresses from (1) product need, such as the need for transportation, to (2) product family which satisfies that need through various modes like cars, trains, planes. (3) Product class further categorizes related goods within a company, while (4) product line refers to a whole range of items in a category. (5) Product types differentiate items within a line, and (6) product units are the last and most specific elements, like the Hyundai I20 Asta and Magna models.