When you see that user Name or Department or other user details are different from what you expect, first thing to check is to verify user profile details in the current site collection.
To open user profile details, open site collection's site settings -> site permissions, find necessary user, move cursor over user's name, right click -> Copy shortcut, it will look like:
build and open another link changing only ID of user:
User profile details can be different in different site collections - this is a usual SharePoint behavior. Because User profile details are written and afterwards stored without changes in site collection from the moment when user was first added to site collection.
At the moment of adding a user in a site collection user profile details are taken directly from AD or SharePoint User Profile service (or other source) and certainly there could be changes in time in these sources. Therefore discrepancy of user profile details in site collections, created at different times, is a usual thing.
In order to avoid such discrepancy SharePoint User Profile service should be configured by your SharePoint administrator properly.
To immediately synchronize user profile details with users source:
run in PowerShell:
$user = Get-SPUser -web http://your_course_url -Identity example\login Set-SPUser -Identity $user –SyncFromAD
Mind that ONLY the “Name” / “Display Name” and “Work e-mail” / “E-Mail” fields are updated with Set-SPUser command. To update the rest, please see following article: http://blog.falchionconsulting.com/index.php/tag/set-spuser/