Gassho!
Following a suggestion by Tony Leith-sensei I hereby open up a cross-forum thread. (*drums rolling*) See the Aikido-forum for details.
Before (and for a couple of months right after) starting Shorinji I practised (among other Budo) Aikido, too. I wasn't very advanced and my knowledge about it is fairly limited.
I did have some trouble with confusing Aikido and Shorinji techniques at the time. This goes to show that, at least to some extent there are similarities between the two (or I'm just that stupid ). But it does, I think, also show that they're not identical. In fact my impression always was, that these similarities were rather outwardly and the principles behind the techniques were quite different.
Starting with the philosophical approaches which are (arguably) in Aikido to restore the harmony between two or more persons, disturbed by the attack, whereas in ShorinjiKempo the focus lies on neutralizing the attack including, if necessary, physical harm to the attacker.
Based on that the technical principles are also, imho, varying: Aikido techniques lean mostly on diverting the attacking force and guiding it into a safer direction, in most cases landing the attacker on the ground. If thus the attack has passed harmony has (at least temporarily) been restored, so no need for pins or additional strikes. In Shorinji on the other hand pain is a useful and therefore valid incentive for ceasing to attack someone. Applying is thus justified and as anyone here knows sometimes done to fair amounts. Whereas this will presumably not restore harmony it will certainly neutralize danger.
The Aikido approach appears to be a bit more passive, with the effect of the technique largely determined by the force of the attack.
This is, summed up, my understanding of the principle differences. Feel free to rip it apart.
Kesshu,
______ Jan.