Windows Explorer uses ID3 tags. Tag handling in Windows depends on Windows Media Player version.
There are two major versions of ID3 tag format - v1 and v2. One file can have separate ID3 v1 and v2 tags. If you change ID3v1 tag only and there is ID3v2 tag present - Windows Explorer will show only v2.
If you change tag with Windows Explorer - it will update both v1 and v2 tags.
It looks like EasyTag application that you showing on screenshot works only on ID3v1 format or you have to reconfigure it to edit v2 tags.
Here you can find detailed information about handling ID3 tags in Windows Media Player 11 (and Windows Explorer if you have WMP11):
link to MSDN
I think older WMP versions support ID3 tags up to ID3 2.3 version, ID3 v2.4 is not supported.