Jujitsu is divided into different ryu, or streams of thought about the material being taught. Over the years, each ryu has divided into smaller streams (ryuha) as students, each with different understandings, have become teachers. The aikido and judo that we do may be classified as descended of kitoryu, daitoryu, and several other ancient ryu down through the ryu of Morihei Ueshiba and Jigoro Kano, down through the ryuha of Kenji Tomiki and into our schools.
So, though it’s really all the same type of material (jujitsu), the exterior form taught in one branch of the family tree often looks very different from the forms taught in another branch. But within a particular ryu, like aikido (Ueshiba-ryu), what differentiates the various ryuha? It is mostly the following three things:
- what is considered fundamental or foundational (kihon)
- what is to be taught explicitly (kata)
- what is implied or assumed to be learned over time (randori)
For instance ikkyo omote is an explicit thing in Aikikai (ikkyo being the first thing you learn, the most foundational technique) but it is mostly just implied in Tomiki. The Tomiki curriculum to some degree assumes that if you happen to get someone fairly close to ikkyo omote then you’ll be able to figure out how to do the technique. Shomenate is another example. Shomenate is an explicit technique in Tomikiryu (indeed, it is considered the most foundational of techniques) but in Aikikai it is mostly implied, or absorbed within other concepts (e.g. irimi). In each system, some material is made explicit and other material is either assumed or is taught in an unstructured way (i.e. in randori).
Hopefully, at some level, the students of all ryuha will progress beyond the foundational material and all the different ryuha will begin to approach the same thing – the ryu – aikido – takemuso aiki - aikijutsu. In my experience, Tomikiryu begins looking a lot more like Aikikai toward the end of the student ranks (sandan). Some of the videos of Doshu Moriteru very much express the same qualities and attributes as Tomikiryu.