If you are ever sick or injured, go watch a class. Closely observe your sensei's technique, then watch as other practice it. There are always differences, some pretty striking. Perhaps due to uke/attack, or to nage's size or temperment... I understood how students could see different things, but couldn't they feel
the same technique as sensei did it to them?
Discussing how techniques feel with a very unsimilar sized/unsimilar temperment colleague of mine, I've since decided maybe part of the reason is how the original students were as ukes... we've all worked with them, and you treat an over-muscled/stiff/heavy footed uke differently than a fast moving/responsive one... I wonder how much styles diverged based on the ukemi of the original students.
Then of course there is a wide range of opinion on how best to teach others... if your dojo has more than one instructor, I'm sure you've noticed how different teachers can be... so depending on what each teacher thought was the best way to transmit ideas/techniques, came different approaches to Aikido.
Or I could be totally off base
I don't think, however, that the differences are a sign of non-union or disharmony (unless we insist on making it so)... I'm the only one with green eyes in my family (a bit scary since everyone else has blue
)... my twin is the only blonde child, my brother the only child with black hair... but we are a family none the less.