Daily Mail headline is "green with envy."
Heavy.com says, "“The color green, according to color psychology, is the color associated with such things as new life, nature, growth, energy and renewal. It’s also the color of money, finances, banking, ambition, jealousy and Wall Street,” reported the newspaper."
Since top-notch designer, Carolina Herrera, made the dress and coat, then the 'different-shades' issue is ok. It's probably lighting or photoshopping.