From my point of view the better is Professional. The most wanted feature is securing Your mailbox that even looking into the files directly You can't read any part of Your mails. I don't know if cipher method is strong or weak though. And with Professional version You get access to travel Voyager client.
cheers, ^ _ ^ Battie ------------------------------------------------------------------------------------ Windows 8.1 Pro (64-bit) | The Bat! Pro 6.0.4 | MailWasher Pro 7.3.0 (Beta)