Ning allows you to create an affordable custom social network and can be a great platform for your fans and supporters to hang out and chat. NationBuilder does many of the things that Ning does, plus gives you a highly customizable public website, a social CRM and email and texting features. A key differentiator is that while Ning is a community platform, NationBuilder is designed to help a leader or leaders move volunteers and loosely aligned supporters towards a common goal. Ning is more about hanging out, and NationBuilder is more about action.