It can sometimes be tricky to know which of these methods are required / most appropriate for the products you’re looking to sell. They all do similar jobs and have some overlap, but they also have some significant differences and use cases. This document will use example use cases to outline the differences between these methods for selling multiple products together and hopefully help you decide which is right for your store.
http://docs.woothemes.com/document/chained-products-vs-product-bundles-vs-force-sells-vs-grouped-products/