ITU specified the rec 709 format used in HDTV systems, whereas SMPTE covers other standards like SDI interfaces or CRT phosphors.

The problem with using a PC monitor for grading is that they usually can't guarantee 100% of rec709, not to mention what windows outputs to the video card is 8 bit video that has been messed with by window's internal color system.

Might want to think about getting a 125 dollar decklink monitor lite for monitoring the video feed, as you'll be able to bypass window's color system and get straight YUV 4:2:2 from AE via HDMI (though your monitor needs to be able to support 10 bit YUV for this to work the best).