The data posted from Wikipedia is slightly misleading in that it lists the empty weight for the An-225 but no others. The Ukrainian beast is still the heaviest by a good margin.
In terms of configuration this is pretty-much a realisation of the Conroy Virtus "Shuttle Carrier Aircraft" design of the 1970s, or those barmy Molniya Heracles satellite-launcher designs of the 1990s. Nothing really new except it was built ( which I concede is a fairly major advance ).
# ep095 Molniya-1000 Heracles : USSR-AIRSPACE, Cosmonaut and Aviation collectibles