Taxonomy and the newer Folksonomy are two very different methods of classification yet similar as well.
Taxonomy is the more traditional method focusing on more strict and formal guidelines. At its fundamentals, it follows a hierarchal structure. Vertical, up or down. This method is effective because of its exact science and specificity there is no confusion. Folksonomy allows sideways definition and labeling. This allows multiple people to categorize one thing in different ways. Although, this allows for more creative archiving, it can get confusing with so many labels to one concept.