NO... just small cosmetic differences that  you would probably never even notice.

The 2004's have painted lower valances as well as the gps antenna. 04 was also the first year for the Ultrasport Package which included 18" wheels, doorblades, and more aggressive bumpers.

The change was 2002-2003, with some transient 2002.5's, more so with the S4 where you have a mix between old drive train and new bodystyle in 02.5

http://consumerguideauto.howstuffworks.com/2002-to-2007-audi-a4.htm

Only minor differences, as a user above mentioned. The B7s went on sale (in Germany) in November 2004.