Tights vs leggings

[PretzelTime]

What's the difference? OK I understand that leggings are more opaque, don't cover feet, and are less dressy than tights. But am I doing some sort of fashion faux pas by wearing leggings with casual dresses. I'm talking those black opaque tights-looking things not jeggings. What's the difference really?

Well, I don't see the point of leggings because they tend to have a big ugly seam running down the inside, and are more likely to fade and go baggy or bobbly than a good pair of opaque tights.