Dome of the Rock is not part of al Aqsa

i've been reading this 'thing' over and over again.. but still dont understand the purpose of making people understand that the Dome of the Rock is not al Aqsa mosque.

erm anyone? please write something.. i'm getting confused here.

please write based on israa mi'raj, and the opening of masjid al aqsa by umar al khattab.. or other related seerah.

anyone??

thanks

w'salam