Here is a comparison of the two, at Onkyo's site. Note that they also have sites in many other languages in case you would be more comfortable with one. Just go to www.onkyo.com and select a location, then go to the Receivers and select the items to compare.
More appropriately, the 1010 features both XT32 + Sub EQ HT (dual sub integration) while the 818 only features XT32. Dual subs can be used in either case, although with the 818, the dual subs would have to be manually level and delay set rather than being done automatically by the Sub EQ HT in the 1010.