Samsung SYNC SGH-A707

Would someone please briefly list the major differences between these two phones to help me decide which to get.

I really don't need music at all, or camera (much); I need a phone that works well: has excellent signal capture, excellent sound, and good battery life.

I was also considering the CU400, but seem to have narrowed the choice to Sync and CU500.

Thanks for the help. 🙂