Additionally,
Boeing 737 and 757 have the same fuselage diameter, 757 has a cigar-shaped aft end, is longer and has a "droop snoot" look. 737 is shorter, appears squatter (original nickname - "Fat Albert.") (Boeing used the same fuselage frame jig for 707-727-737-757.)
Most 737-823 and 757-223 have or will have Aviation Partners Boeing blended winglets - they stick up like a vertical stabilizer at each wing end. (These will probably appear on all 767-323ERs as well, the ones with more exit hatches.)
777 has a "screwdriver end" aft end with Plexiglas, is the largest aircraft AA has.
767 (767-223ER "domestic" and 767-323ER "international") is smaller, yet widebodied, and has a cigar-shaped aft end.
(-x23 is Boeing's numeric designator to show who the aircraft was built for; AA got rid of the 757-231s built for TWA they subsumed when they took over TWA.)
A300 has, as others have pointed out, a wide-bodied stance and wedge-shaped wing ends - possibly not as effective as Airbus would like, or they would not be testing APB Winglets for the A320 series aircraft.
MD-80 is the only aircraft AA has with a long, slender fuselage, engines mounted aft and a screwdriver-tip aft end (modified from the original design.)
In the longer run, say "hello" to more 737-823s, and "goodbye" to the thirsty and aging MD-80s.
The Boeing 787 is coming to AA... some day.
The Boeing 888 is, well, have a look... and
not coming to AA (or KLM)
Lots of aircraft photos at
www.airliners.net
Q. "What's the difference between a 777-223ER with Rolls Royces engine and an Executive Platinum?"
A. "The 777 stops whining when it shuts down at the gate."