The DC10 was made by McDonnell Douglas, the L1011 was made by Lockheed. The most noticeable difference is the #2 (tail) engine. The DC10 has the banjo-style (the engine goes straight through the tail fin, if you looked at it from the front, it would look much like a banjo shape) fitting. The L1011 has the S-Duct fitting, much like that of the 727. The L1011, while more advanced and somewhat safer with 4 hydraulic systems, not 3 like the DC10, flopped because Rolls-Royce was the sole engine designer for it, and they almost flopped themselves, setting the whole program back. In the meantime, United, American, Continental, & many others went for the DC10 instead. Both had 3 engines, 3 crewmembers, and a twin aisle cabin with 2-2-2 (first) & 2-5-2 (economy) seating.