Here's something cut and pasted from another forum:
Versions of Windows;
Windows Trial - Only allows you to run one program, expires after 30 days, can't be upgraded, no networking code included, doesn't allow multiple users.
Windows Preview - Only allows you to run one program, no networking code included, doesn't allow multiple users.
Windows Basic - Allows running unlimited number of programs, no networking code included, doesn't allow multiple users.
Windows Networking Trial - Same as Windows Trial, but includes networking code.
Windows Networking Preview - Same as Windows Preview, but includes networking code.
Windows Networking Basic - Same as Windows Basic, but includes networking code.
Windows Multi-User Trial - Same as Windows Trial, but allows up to 3 users.
Windows Multi-User Preview - Same as Windows Preview, but allows up to 3 users.
Windows Multi-User Basic - Same as Windows Basic, but allows up to 3 users.
Windows Multi-User Networking Trial - Same as Windows Networking Trial, but allows up to 3 users.
Windows Multi-User Networking Preview - Same as Windows Networking Preview, but allows up to 3 users.
Windows Multi-User Networking Basic - Same as Windows Networking Basic, but allows up to 3 users.
Windows Pro Trial - Same as Windows Multi-User Trial, but allows unlimited users.
Windows Pro Preview - Same as Windows Multi-User Preview, but allows unlimited users.
Windows Pro Basic - Same as Windows Multi-User Basic, but allows unlimited users.
Windows Pro Networking Trial - Same as Windows Multi-User Networking Trial, but allows unlimited users.
Windows Pro Networking Preview - Same as Windows Multi-User Networking Preview, but allows unlimited users.
Windows Pro Networking Basic - Same as Windows Multi-User Networking Basic, but allows unlimited users.