Just something I've been wondering

[rock_dinosaur]

Pantyhose isn't a word that's used in the UK; we think of pantyhose as being the American word for what are universally known here as tights. However, I recently saw someone saying they wore tights when they were younger and didn't start wearing pantyhose until they were older, as if the words referred to two different things. Maybe they just didn't realise that both words mean the same thing? Or maybe they do have different meanings that I've never been aware of? So I'm wondering:

Poll Tights vs. pantyhose
If tights and pantyhose aren't the same thing, what's the difference between them? Can anyone explain?

[Update: this has certainly been a learning experience. Thanks, everyone! I'm glad I asked now.]