If you want to build your affiliate center for your various products, ECM can be a great solution for you. Those products should not have any connection at all (imagine products lining up in horizontal line and have same price line).Originally Posted by Mike Merz
With scripts like BM, you can only build an affiliate center for one particular product or a series of products that closely related (imagine products lining up in vertical line and they have different price structure. You customer coming and buy lower price product, then they are introduced to a much a higher price product and so on).
Like Mike said you can use both for different purposes.