The differences are outlined here:
https://www-secure.symantec.com/connect/articles/difference-between-symantec-endpoint-protection-121-symantec-endpoint-protection-sbe-2013-a
Basically SEP SBE is for small companies meaning fewer than 100 employees.
At it's basic level it contains antivirus, intrusion prevention, and a firewall. These are the minimum you would need to secure your business and will probably work best for you. Review the requirements and let me know if you have questions.