In this picture I have compared Pinterest and Amazon with the use of the six dimensions of social media according to Marsden from Sygygy Group. Probably all arguments speak for themselves accept maybe those from the Social Media Optimization (SMO):
Companies can use pinterest to optimize themselves through social media. Amazon uses other social media to optimize their own company. It just a different perspective.
So let me know if you (dis) agree with my arguments and maybe add some suggestions!
Marjolein