drgondog, the way it has been described is that the USAAF area bombed precision targets and the RAF precision bombed area targets.
The fact of the matter is that bombing in formation, as the 8th did, resulted in bombs dispersed over an area. If the lead bomber was any good, hopefully the area would be centred on the target.
The 8th did participate in area bombing, but not as often as the RAF.
The effects of Harris' city busting campaign are not immediately obvious. But it did divert a lot of resources into dfending cities at night, prompted the increase in production of flak guns at the expense of other fiield equipment. Just having the air raid sirens go off in the night also disrupted the lives of the public, many of who were in industries helping teh German war effort.
Also, towards the end I believe the 8th basically carpet bombed the synthetic oil plants.