If you have more than one teacher you will run into contradictions. Or rather, you will hear things that may sound different to your ears.
Many years ago I had one teacher explain in great detail the difference between each level of Muso Jikiden Eishin Ryu Iai, the timing of the choice point between cut and don’t cut, the height of the cut, the angle of the lift over the head, the timing and position of noto. At around the same time I had another teacher answer my questions about differences between the levels with a puzzled look and the statement “there are no differences”.
After a while I came to understand that they were both correct, and I’ve used this story as a koan for my students and as a reminder to reconcile all my instruction from all my teachers. In very few cases have I found any actual differences between instructors, just different ways of expressing the same underlying principles.
Take a while to think about the koan above if you’d like, then come back and read the rest.
The answer is actually quite simple, and as in most things, is helped by a slightly different definition of the question. Are there differences in the way you perform the kata in each level of MJER? Yes there are and no there are not.
Yes there are, in any physical skill there are levels of ability that can be demonstrated between beginners and more advanced students. To teach efficiently and correctly an instructor will introduce simpler skills before more advanced skills. So in a specific case, we might look at the speed of the noto, the putting away of the sword into the scabbard. Omori ryu / shoden (the first level) starts slow and uses the whole sword during the movement. Oku iai (the third level) uses a very fast noto and about a third of the sword during the movement to line the sword up for this quick insertion. Eishin ryu (chuden) the middle level uses half the sword and a slow insertion, so somewhere in between in skill demand. This is a way to teach progressively and so yes, there are differences in how you perform the kata depending on which set you’re doing.
No there are no differences, in any physical skill there are levels of ability that can be demonstrated between beginners and more advanced students. This means that at early days in your training (when you are working on Omori for instance) you will be performing at a certain skill level. As you advance in skill and through the levels you will become more fluent, more able to perform actions swiftly as well as correctly, and so you can perform, say, the noto with speed and efficiency. Does this mean that you have to dumb down your skills when you perform Omori ryu if you can perform Oku iai with superior skills? No of course not. You perform whatever kata you are demonstrating to the limit of your ability, Omori ryu kata have a slow noto and Oku kata have a fast noto, this is the way they are performed, you do each to the best of your current ability.
Oh you say, that’s no koan, that’s just a bit of a trick in definitions. Well yes, and that’s what a koan is, a way to get you to see that the world is mostly full of different rationalizations, different definitions within your head, but is a much simpler place than you might want to believe. Enlightenment is mostly seeing the unity of the cosmos behind the confusion and illusion of definition after all.
Too woo woo? Well go find your own contradicton in instruction and see what you can do about justifying two of your admired teachers telling you different things. It might be that they got together and decided to torture you with a paradox, or it may just be that a small adjustment of definition in your own mind will reconcile the worldview.