Question about Live view....
In live view, the camera looks (though the sensor) at the image to ensure that the area is sharp. It literally focuses until it sees it sharp by way of contrast detection.
In normal viewfinder focusing, the phase detect sensor sends a signal to the lens to adjust itself to where it should be in focus. There is often a small difference between what the phase detect sensor detects and the focusing information it sends to the lens.
If you see a difference between live view (contrast detection) and when using the viewfinder (phase detection) than you probably need to calibrate that lens with that camera.
It's more important how an image looks as a thumbnail than how it looks at 100%.