The IBM 5153 Personal Computer Color Display was a monitor designed to accompany the original IBM PC (albeit released a couple of years later) and provide a color display at sharp enough resolution to be usable with 80 columns of text.
Of course in principle you could use a color TV, but the fine detail was blurry and marred by NTSC color artifacts, so that it was problematic trying to work with much more than 40 columns on such a setup.
The reasons for the difference at the electronic level are clear: Some picture clarity is lost in the RF encoding phase, more in the encoding of color in the chroma signal that was necessary for backward compatibility with black and white TV sets. But what were the differences in the actual picture tube?
If you took all the electronics from a monitor like the IBM 5153 and substituted just the picture tube from a color TV, what would still be lacking in terms of display quality?