How do you distinguish between an Airbus and a Boeing?

Generally Airbus has engines which go under the wing, where Boeing tend to mount them forward of the wing

Airbus aircraft appear to be quite 'stalky' standing on their landing gear, like some sort of wading bird, and the nose is more blunt looking than Boeing aircraft. Depending on the operator, many Airbus aircraft have winglets on the wing tips also.

An easy to spot difference are the cockpit Windows, and most Airbus aircraft have wingtip "fences" at the end of the wing, while Boeing uses winglets, or sometimes "raked wingtips."