Um, not true. I don't see much of a difference in those screenshots. But when I pop my BD in my player and watch it on my HDTV, it looks simply amazing. I am wowed. These screenshots fail to wow me in the same way, which is odd being that these pics are captured from the same BD.
TVs can be punchier with the colors and contrasts. Monitors can be more accurate even to the point of feeling lifeless in comparison. So your observation makes perfect sense to me.