What is the difference between Windows XP Professional and Home editions ?

The Home and Pro editions of Windows XP are nearly identical; with some additional features found in the Professional edition that are only likely to appeal to users in a more sophisticated network environment. The primary differences are as follows:

Windows XP Home Edition
Peer-to-peer networking up to five computers
Backup utility not installed by default
Basic support for security among multiple users

Windows XP Professional Edition
Better networking support, with the ability to join a domain
Support for multi-processor systems (2 or 4 CPUs)
Administrative Tools (in the Start Menu and Control Panel)
Automated System Recovery (ASR)
Support for dynamic disks
NTFS Encryption Utility
Group Policy Refresh Utility
Backup utility installed by default
Extended security support between multiple users on the same machine
Performance Log Manager
Remote Desktop
Scheduled Tasks Console
Security Template Utility
Telnet Administrator