As rchowe said, the different formats are mostly used in higher math and have semantic meanings specific to that context. These should almost never be used out

As rchowe said, the different formats are mostly used in higher math and have semantic meanings specific to that context. These should almost never be used outside that context as they have different byte values from the usual Roman characters (which means the computer doesn't even see them as equivalent without "help" from the programmer), may not be supported by every browser or text search program, and may not even render correctly on many OS systems as the glyph for that character may be swapped in for a glyph from a different font or not at all for older systems.