A380 is complete double-decker (I remember Boeing had similar idea named B2707.) with 4 engines. Because 380 has 9 full-sized exits on each side, airliners can put up to 990 seats on this airplane, but Airbus proposed standard 3-class configuration made of 555 seats, so it's far safer than formal 744 (400 seats normally, up to 580) or 773 (350 seats normally, up to 550). By Airbus's figures, it's wingspan is 79.3 meters, 15 meters longer than 744. For addition, it's fuselage is shorter than both of 773 and 346. Because it's big, 380 will have engine with 1.8x thrust of 744, so there's no problem for takeoff, unless one of wings are broken away.
But, but, first of all, I'm talking about 380, which was 3xx formerly, but what's A3xxx?