The quick answer to your question is no.
Granted, a little will be determined from what speakers you get.
The 1015 does have a tad more power and cleaner
(however, power numbers mean little - unless you like to listen at reference to above levels)
1015 offers video upconversion
1015's remote is a learning remote (compared to a preprogramed remote)
1015 has THX Select2 certification (this has been covered extensively)
1015 has the flip down door (aesthetically much nicer)
1015 weight is 34.7 lbs 815 is 22.4 (better build on the 1015, better power supply, etc..)
1015 has the OSD (on screen display) Great feature to have for adjustments, specially the individual speaker 5 band EQ.
The 1015 has more composite & S-video inputs (more than likely only half would be used anyway)
1015 has digital output
The 815 has one extra soundfield
The 1015 uses a Mosfet Transistor the 815 uses a Thermal Compensation Transistor
For explanation of these - see links.
http://en.wikipedia.org/wiki/Compound_transistor
http://en.wikipedia.org/wiki/Mosfet