Fancy Script Generator
This row is bold script, running from U+1D4D0. It matters for one reason: it is the complete script alphabet, so no letter is missing and none has to be borrowed from another part of Unicode.
These are characters, not formatting, which is why they survive a paste into a bio. It is also why a screen reader will not read them as ordinary letters, and why some sites refuse them in a name field.
The script set with no holes
Twenty-six capitals from U+1D4D0 and twenty-six lowercase from U+1D4EA, all assigned, all drawn by the same hand. Plain script is not like that: eleven of its letters were left unassigned and have to be taken from an older block. Type the word Message in both rows and the difference shows, because M, e and g are three of the borrowed letters in plain cursive and none of them are borrowed here.
When the two rows look identical
On a device whose fonts cover neither range properly, both rows fall back to the same substitute face and the difference disappears. Where the fonts do cover them, bold script is visibly heavier and rounder than plain script. Check on the phone you actually intend to paste into, because the rendering, not the codepoint, is what your reader sees.
No digits, and accents stay plain
The bold script range carries letters only. Numbers come back as ordinary digits, and accented letters, which have no script form anywhere in Unicode, pass through exactly as typed. If numerals need to match the letters, bold is the style that has its own.
What it costs
These are characters rather than a typeface, which is why the look survives a paste, and also why a screen reader announces MATHEMATICAL BOLD SCRIPT SMALL A instead of reading the word. Use it for a decorative line, never for the substance of a post or for a name someone has to say out loud, and expect that no ordinary search will match it. Every other style is on the styles page.