I have a mac mini running windows 8 these days, but it is the same issue on OS X regardless.
There are a variety of ports on the back of the mini, and currently I'm using a thunderbolt connection that uses a converter to VGA. I have the exact same two TV's, Samsung SyncMaster TA550. The the VGA resolution for my first screen is perfect, crisp. But the second monitor uses a hdmi cable as there is only one thunderbolt port. But this display doesn't fit the screen and is also a little blurry.
Both according to windows 8 are displaying the exact same resolution but different results.
Any ideas on a fix?