One thing I really like about this hobby is while the principle idea of kites is simple; a piece of fabric and sticks tethered and controlled by a length(s) of string; the details of flight are quite complex.
As JimB points out, there are lots of static factors involved: center of gravity, aspect ratio, wing span, height, sail shape, sail loading, tunnel depth, standoff number and placement, trailing edge profile, leading edge shape, frame weight and stiffness, frame geometry, weight distribution, bridling and all its nuances. Don't forget broad seaming, venting, etc, etc....
Then there are all the dynamic factors: sail pressure, center of pressure, lift, drag, boundary layer, Reynolds numbers, angle of attack, turning radius, inertia, fabric vibration, frame flex, wind speed and smoothness, 2 dimensional flight (carving turns, corners, figures), 3 dimensional flight (tricks, flailing, falling with style), etc, etc.
What about pilot skill all thing being equal?
The craft and art of building kites is a world unto itself.
After applying the best aerodynamic engineering principles towards a particular design there is still the need for prototyping, test flying, tweaking, lather, rinse, repeat...
I do not understand all the factors involved in flight but the observable simplicity of flying a kite is a thing of beauty.