The difference between the AVRO 504K and the AVRO 504N are, amongst other things:

1. A New” Oleo” undercarriage is fitted.
2. An adjustable Tail Plane arranged for dual operation, enabling the machine to be trimmed for different speeds and varying loads.
3. Altered Centre Section Plane and Wing Roots, allowing a much greater range of upward and forward vision.
4. New shape Ailerons to lighten and harmonise the lateral control with the elevator and rudder controls.
5. Direct gravity feed for petrol.
6. Different shaped fuselage section.
7. 6 inch shorter (from what I see).
8. New engine.

It is worth noting that the AVRO 504K Mark II was very similar to the AVRO 504N, but with the original rotary engine.