In short the security on BES is higher (AES256+ plus unique session keys), you can encrypt the device content, you have over 600 I.T polices to fully control the device, simple management interface, secure connection back to your network (e.g. you can access your intranet from the device), All data can be tunnelled back to the office including internet (this gives you unlimited data access as part of your plan), internet access can be pointed to your proxy and web filter, application can be pushed wirelessly to an individual or group. There are many more features but this gives you a general overview of the differences.
