One difference between XP Pro and XP home is security. Windows XP is security. Windows XP Home Edition comes with basic support for security among multiple users. That means with the Home edition, anyone who logs on has total control and therefore is not extremely useful in security.
The target market between the XP and Home XP is different. With Home edition, Microsoft is targeting directly at consumers and homeowners. On the other hand, Windows XP Pro is aimed at business users and power users.
Pro was created for corporate networking. It has extra features that are not included in Home. With Windows XP Pro Edition, better support, which is included for security between multiple users on the same machine. Other features missing from the Home edition includes back up operators, power users, and power groups.