Flamboyant Natural vs Flamboyant Gamine
Flamboyant Naturals are basically the larger version of the Flamboyant Gamines. The biggest difference is physical presence and that FNs have complete elongation, instead of only partial like the FG.
Flamboyant Natural vs Dramatic Classic
Also a pair that is similar in energy. Flamboyant Naturals can have a very muted image, which does make some doubt they are a Dramatic Classic. But, if you go purely by shapes they are very different. Do you have blunt shapes? Then you are most likely a FN.
Flamboyant Natural vs Natural
Another pair that is very similar! The biggest difference between these two is physical presence, FNs look very strong and robust while Ns are more balanced. Elongation is also a good pointer. If your shapes are long and stretched out, FN is a better fit. If you are still doubting, look at your face. The Natural has a balanced and even face while the FN has a face with a wider mouth, wide bone structure and sometimes even wide set eyes!
Flamboyant Natural vs Extravagant Natural
I think most people are doubting between these two because they are not sure if they are Lush enough for the Extravagant Natural. The best way to find this out is to do the shape drawing and see if you have rounded shapes, FNs barely have any rounded shapes. If they are a big part of your overall image EN would probably be a better fit. You can also see if that Lushness is apparent in your face, if you have very full facial features, EN would also be a better fit.
Flamboyant Natural vs Dramatic
These two have a lot in common, both are made up of strong shapes and have a very elongated image. If you are stuck between these two, the shape drawing is the easiest way to find your type. Ds are completely sharp while FNs are completely blunt.