If you take a screenshot and blow it up you’ll see something like this:
The text of lines 34-36 are subpixel antialiased. Line 37 is not. You can tell it is subpixel antialiased because one side of the characters will be shifted red and the other side will be shifted blue. The direction of the shift is dependent on the monitor being used.
You can find more information on subpixel rendering on Wikipedia.