The defiant young person, at least at a very early age, probably has the same desires as the obedient one, but he is willing to fight for them. This, as you noted, is the only real difference.

As the defiant youth gets older, a good parent will (and not by authoritarian means) attempt to shape and mold his desires in to something worth while. The four year old who demanded the toy in the supermarket may become an eleven year old who demands social justice, and he may become an eleven year old who demands money and things like that. The defiance should be embraced and channeled, not squashed.
But defiance is not embraced, molded, and viewed as a logical attitude. It is seen as a disease and a character flaw. Folks in the movement complain about the word child, but I think that after minor, ‘brat’ is the most offensive word used to describe us. People actually take Oppositional Defiance Disorder seriously. That eleven year old demanding social justice will probably be sent to a gulag school.