Aikijitsu? Aikido? Ju-jitsu? huh?
Fundamentally, it breaks down like this: there are two ways to interpret it- whenever you have a "do" at the end of a word (Aiki"Do" for instance), it means Way, as in the "Way of" whatever. So, karate- do is "The Way of the empty hand"; Aikido is "the Way of Harmony with the vital force of the universe"; Jeet Kune Do is "the Way of the intercepting fist", etc., etc.
Theoretically speaking, The Way implies a series of philosophical/ ethical considerations for the practitioners of that particular art. On the other hand "Jitsu" means roughly "technique", "group of techniques" or "the Art". Therefore, the "Techniques" do not necessarily imply a philosophical background, but rather are solely a group of techniques that help you do something, like say, defend yourself.
The other way of looking at it is considering that every Do implies a Jitsu, but not every Jitsu implies a Do. The techniques of Aikido, stripped of their ethical/ philosophical underpinnings are Aiki Jitsu. Shiho-nage, Kokyu-nage, Nikkyo, Sankyo, etc. are all techniques -Jitsu-. When you add to them the ethics of Aiki, i.e. defending yourself while protecting your opponent, the uniting of the family of man through the practice of Budo, etc. THEN you have AikiDO. And so on with all the other DOs there are.
This is, of course grossly simplifying matters, as the line between Do and Jitsu Arts is not so cut and dried, specially as the practice of any martial art almost necessarily implies a certain mindset within the Art practiced that can be called "philosophy" or "ethics".
On a concrete level, Ju- jitsu differs from Aikido simply in that it is a different martial art (albeit a founding pillar of Aikido in the form of Daito -ryu Ju- jitsu, along with kenjitsu and Omoto-Kyo among other things), wherein, depending on the style, there is an emphasis on atemi, kicks, joint locks and grappling. In japanese it means "the Gentle Art" and was developed by buddhist monks as an empty handed means of defending themselves from bandits that plagued their routes of pilgrimage; particularly because in buddhism the use of weapons was prohibited.
To further muddy the waters for you, I will mention that some people call Aiki Jitsu the mix of Aikido and Ju- Jitsu (as in AIKIdo and ju- JITSU).
Like I said, this is really an over-simplification of reality. The actual lines blur and become indistinct between Do and Jitsu. So really the difference is irrelevant. Remember no Martial Art is ever more than what YOU put into it.
Hope this helps a little.
[Edited by stratcat on October 2, 2000 at 12:48am]