PIL not rendering fonts uniformly across machines

Answer 1

I would guess that the top image was rendered with the TrueType hinting bytecode VM enabled, where the bottom was using only FreeType's auto-hinting. (Personally I prefer the bottom!)

There are, unfortunately, software patent issues which mean the hinting bytecode feature is not available on all binary builds. This is why it's not a simple run-time feature you can enable and disable, but something that is decided at compile-time. If you compile your own copy of FreeType you can enable the feature by #define-ing the flag TT_CONFIG_OPTION_BYTECODE_INTERPRETER in config/ftoption.h — if your lawyer reckons it's a good idea.