Originally Posted by closetasfan

similar size to MD 80 with two engines on the wings = 737, short/lower to the ground and two sets of wheels on each side of the aircraft.

a little longer, distinctive face = 757 two doors forward of the wing on each side, slender, two sets of four wheels that are tandem on each side

bigger with cone tail = 767 one door forward of the wing on each side, fuselage is not slender, two sets of four wheels that are tandem on each side. Furthermore there are 2 variants of the 767 in the AA fleet.

bigger yet with flathead tail = 777 two doors forward of the wing on each side, two sets of six wheels that are triple on each side (easiest way to tell)

A300 - no idea. Available for a limited time at MIA, JFK, and SJU (US stations), look under the wings and you will see several humps (don't know the proper name), tail of the plane tapers up on the underside differently than a 767, not sure how many wheels (2 sets of 4 tandem?) and the end of each wing has a fence-tops that are shaped like diamonds; as opposed to winglttes that extend up only...this a/cwill be leaving the AA fleet after this summer
distinguishing between different models within type, no idea.see bolded notes next to each