Rodeo's are done fully inverted, and Flatspins aer essentially the same trick, save that the rider does not get 100% inverted (feet directly above head). That said, yes, the line between them is very blurry, especially with a 540 rotation (7's are somewhat easier to tell). I would call what you did a flatspin, as you were close to complete inversion, but not all the way there. As for turning your flatspins into true rodeo's, try and drop your arm/side more when you take off. Dont lean back with your back like you would in a backflip, that causes the flat rotation.