Whilst the outfit on the left is not an absolute no-no there is no question that the outfit on the right is so much better. With regards the outfit on the left: Avoid wearing a shapeless top with a shapeless skirt, you will look shapeless. With regards the outfit on the right: The same top, with a dropped waisted belt and skinny jeans (or tapered pans if you can’t wear skinny jeans) has more shape. The draping over the bust area will enhance a small bust or conceal a full bust (one of the few styles that does both). The draping over the tummy will disguise a rounded tummy.
The answer to this fashion Q&A was provided by Chata Romano