"quotation marks" and "inverted commas"

What is the difference between "quotation marks" and "inverted commas"? Or they are the same?

Quotation marks are often called "inverted commas" in UK. They are the same thing.

Quotation marks are (any) symbols used to define quotas. Inverted commas are just symbols, sometimes used as quotation marks. As simple as that :)

Brits use single marks, ‘like this’, so they are really very similar to commas. Americans use double marks, “like this”.

Brits use double marks for quotes inside qoutes: `Like ``this'' one'. All these marks can be called inverted commas. In US the use is exactly opposite: ``Like `this'. ''.

Most book/magazine publishers are more likely to print '_________' instead of "________".

I always start a quote with the doubles, and, if appropriate, use the singles for 'sub-quotations', e.g. "__________, '_____', __________".

I like single quotes (apostrophes) because they don't need the Shift key :D

It really doesn't matter whether you use one ore two marks, just so long as you alternate:

"she said, 'hello,'" I said.
'she said, "hello,"' I said.