The one thats been one my mind since the Final Arc started is why Ivan didn't like being called an Arrancar.
Here's My Answer For Why Ivan Wasn't An Arrancar: Arrancar's were introduced by Aizen as the new highest form for a hollow to possiblely acheive, despite having an human apperance they carried a zakpakto which enabled to them to active a hidden form/orginal form becoming soul reaper like.
A few arcs later a man by the man of Ivan is seen confronting & fighting Ichigo. His apperance was similar to that of an only of accessible use for the "chosen ones: White jacket & a small piece of an remaining hollow mask.
So back to my theroy. During Ivans and Ichigo, Ivan give everyone a big surprize by unvieling a HUGE Quincy Bow. He also ststed something on the lines of "Why wouldn't your Bonkai Disapper". Lastly seen fleeing the battle using a techquie called Shadows wich is accessible use for the "chosen ones".
These were not something an Arrancar posesed or could do. Making Ivan something much than just an Arrancar, or at least thats what Ivan thought.
But it wasn't until he returned to his secert lair and after being killed by his leader, The Buckbeard he was labelled as an Arrancar (were this contoversy began), he was lablled "an Arrancar" ? because The Buckbeard just viewed him as an Evoled Hollow who was sent out just to fight and most likely also didn't care about him because he wasn't within some of the strongest within his army. The next Chapter reavled an new Arrancer who spoke to The Buckbeard on Equal Terms, meaning that is much more stronger than Ivan.