According to PC magazine

Subject: According to PC magazine
Name: Sledge
Date: 11/6/2001 4:58:39 AM (GMT-7)
IP Address: 12.159.32.18
In Reply to: 'Pro' mainly adds extra power lines if I am not mistaken (nt) posted by ludicrous
Message:

There are two standards for AGP Pro. AGP Pro 50 and 150. The numbers stand for the extra number of watts delivered to the card. Regular AGP has 25W.