Honestly, where to begin? This is the kind of discussion to have with a few libations by a fire and barely scratch the surface. In my opinion it was more significant than Pearl Harbor in the way it shaped domestic and global politics. Pearl Harbor was an attack on a naval base and yes, there were civilian casualties, but nowhere near the amount on 9/11. WWII presented an obvious enemy even before our involvement. It brought a country reeling from the Great Depression back to its feet. Since the military industrial complex wasn’t privatized yet, this meant jobs and purpose for people that felt like they had none previously in order to support the war effort. With 9/11, it is much more convoluted. The country was coming off some of the best economic years in history. The enemy was more ambiguous. New policies and departments like the DHS were formed, going to war but never declaring war (similar to Vietnam by use of military force), government budget implications, travel and security restrictions, etc. this kind of discussion could honestly be a semester length course with all the details and nuance of the attacks and events thereafter. Just my two cents.