BMWs model lifespan is about 7 years from introduction of mass production to the end of it... somewhere in the middle of the 7 year span, the factory updates the look by changing shape of lights, tails, some minor things.. it is called Life Cycle Impulse , LCI... for the X5, it happened in MY 2004, when a new V-8 was introduced, the N62 in place of M62 (M62 has been in the BMW line up since early-mid 90-s, which itself got its own revisions from no VANOS to single VANOS to double VANOS).

instead of calling these models LCI folks just call them facelifted, i guess reference to a plastic surgeon lifting up old face to make it look young!!!