This interesting article compares the font rendering technology of Microsoft and Apple.
Yet…
Why does everybody forget about the big dog down in San Jose which represents most of what we see? If you have looked at a PDF, a Flash application, or a web site that had text rendered to gif/png by Photoshop.. then your seeing the result of the Adobe font renderer. I would bet that the output would look pretty similar to Apple’s renderer since Apple licensed their technology and NeXT originally used Display Postscript.