Whats the difference between Mail Essential and Mail Security ?

Cut the long story short here is the detail in point form...

What Mail Security does that Mail Essentials doesn't do:

• Virus checking with multiple virus scanning engines
• Email exploit detection engine
• Approve/Reject quarantined mail using the moderator client/email client/public folders
• Apply rules to AD users or groups
• Lexical analysis
• Enabling Event Logging for the Virus Scanning API 2.0 Exchange 2000 only (This information can be found in the microsoft Knowledgebase (Q294336)).
• Setting Virus Scanning API Performance Monitor Counters

What it Mail Security doesn't do that Mail Essentials does do:

• Company-wide disclaimer/footer text
• Mail archiving to a database
• Reporting
• POP3 downloader
• Personalized server-based auto replies with tracking number (win2000 only)