And if we're to discuss just how chocolate icecream is different from other icecreams, we're in trouble. Because there's so darn many kinds of chocolate ice cream! With chocolate chips in it, and without, and light brown or really really dark... Training in Iwama Ryu or in Ki Society - is it the same art? In a way, yes. But there are plenty of people who love one of the varietes and wouldn't touch the other with a stick. OK part of that is prejudice, but only part. The differences within the aikido umbrella is hugh.
I could try and define what I think is fairly unique about the line of aikido that I consider mine. But less than 5% of the participants of this board would then agree that I was describing "aikido". Some might even assume I was describing "bad aikido".