Interesting. It says they're the same thing, but then the two characters listed on the page (the regular backslash and the Unicode variant) are rendered noticeably differently.
Look at the HTML. The "unicode variant" is rendered differently because the code tells the browser to render it differently, not because it's a different character.
I can't imagine why they changed the name, given that the forward slash and the solidus are not interchangeable. http://www.fileformat.info/info/unicode/char/5c/index.htm