Not sure if you can download both Windows and Mac. They are making installation changes this year and you get a License Code even with a CD.
There aren't any differences in the tax part of the program just in running the program. The Mac version automatically checks for updates each time you start. With Windows you can select update options.
The Mac version automatically saves your return. In Windows you have to manually save it although it will ask if you want to save when you exit or start a new return.
There is a difference in the Home & Business if you want to prepare W2s or 1099s. If you are using the Mac Home & Business CD/Download program you can only prepare W2s and 1099s using the Online QEF - Quick Employer Forms. In the Windows Home & Business you can also prepare them locally on your computer in the built in W2/1099 Reporter.
Thats all I can think of right now.
