Just this morning, I installed SQL Server 2008 Express SP2 from the Web Platform Installer. When I went to restore some databases, the error message was that my database files are from version 10.5 and I have version 10.0.4000. I tried downloading this file from Microsoft, but it errored out saying that I don't have anything to upgrade in my machine.
I ran this code:
SELECT
SERVERPROPERTY('productversion') as 'Product Version',
SERVERPROPERTY('productlevel') as 'Service Pack',
SERVERPROPERTY('edition') as 'Edition',
SERVERPROPERTY('instancename') as 'Instance',
SERVERPROPERTY('servername') as 'Server Name'
And got back this:
10.0.4000.0 SP2 Express Edition SQLEXPRESS DEV-PC1\SQLEXPRESS
I believe you're fine and patched up to date, just slightly confused on nomenclature. Fantastic job btw on finding and running that query, many folks don't go to that effort.
Despite the similarity in names, SQL Server 2008 (10.00) and SQL Server 2008 R2 (10.50) are distinct versions of the product SQL Server. The Edition, denotes the product license, in your case, Express.
A Service Pack, SP, is a collection of Cumulative Updates, CU, and usually some minor feature fixes/improvements. To further muddy the waters, a Hot Fix or QFE is a software patch that is focused on fixing a specific issue.
The best list for tying versions to available fixes is this site, SQL Server Version Database At this time, you are at the current Service Pack level "2008 + Service Pack 2" as your version number indicates (10.00.4000) There have been 4 Cumulative Updates released since then SP2 and a QFE (which patches an XML vulnerability)