When you use Enterprise Mode on Internet Explorer 11, the site text width will be rendered slightly different compared to Internet Explorer 8.
This issue occurs because natural metrics is set to turn on by default in Internet Explorer 11.
To fix this issue, install the most recent cumulative security update for Internet Explorer. This update will disable natural metrics when you browse a site in Enterprise Mode. To do this, go to Microsoft Update. Additionally, see the technical information about the most recent cumulative security update for Internet Explorer.
Note This update was first included in the November 2015 security update for Internet Explorer (MS15-112).
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
See the terminology that Microsoft uses to describe software updates.