It's the fact that Windows basically requires well-hinted fonts in order to render well, since Windows has always tried to render fonts to match up with pixel boundaries.
OSX, on the other hand, anti-aliases fonts perfectly, and thus has no need of hinting at all. It's a philosophical difference as to which looks better.
BUT, the recent trend is in starting to use non-system fonts in web design, now that the Google Fonts project has taken off (together with widespread browser support for custom fonts).
The problem is that freely available fonts generally either have no hinting, or "automated" hinting -- because well-done hinting is incredibly time-consuming and, in the age of "retina displays", slowly losing its usefulness.
So, all these web fonts that render beautifully on OSX look like crap in Internet Explorer, since they have no hinting. (It actually bothers me so much that I run GDI++ on my Windows computer at work -- it renders all fonts Mac-style without hinting, instead of Windows-style.)
OSX, on the other hand, anti-aliases fonts perfectly, and thus has no need of hinting at all. It's a philosophical difference as to which looks better.
BUT, the recent trend is in starting to use non-system fonts in web design, now that the Google Fonts project has taken off (together with widespread browser support for custom fonts).
The problem is that freely available fonts generally either have no hinting, or "automated" hinting -- because well-done hinting is incredibly time-consuming and, in the age of "retina displays", slowly losing its usefulness.
So, all these web fonts that render beautifully on OSX look like crap in Internet Explorer, since they have no hinting. (It actually bothers me so much that I run GDI++ on my Windows computer at work -- it renders all fonts Mac-style without hinting, instead of Windows-style.)