The first pair is separated by a thin space (U+200B), the second is pure.
Both should render identically.
All listed fonts offer a native U+200B, except the ›Vista Fonts‹
Calibri, Candara, Cambria, Consolas, Constantia and Corbel.
| Font | HB | HB |
|---|---|---|
| (none) | HB | HB |
| Adobe Jenson Pro | HB | HB |
| Antique Olive Std | HB | HB |
| Arial Unicode MS | HB | HB |
| Arno Pro | HB | HB |
| Calibri | HB | HB |
| Candara | HB | HB |
| Cambria | HB | HB |
| Consolas | HB | HB |
| Constantia | HB | HB |
| Corbel | HB | HB |
| DejaVu Sans | HB | HB |
| Futura | HB | HB |
| Gentium | HB | HB |
| Linux Libertine | HB | HB |
| Lucida Sans Unicode | HB | HB |
| Segoe UI | HB | HB |