kendo w/o armour? aiya! its hurts me just thinking about it
(As a side note, there is debate whether it's -jitsu or -jutsu. They mean the same thing, its a result of translation around how people pronounce the words. I generally pronounce it jutsu, but spell it jitsu. You'll see and hear it both ways though)
Technically, Kendo is a sport derived from Kenjitsu. The Japanese sufixes -do and -jitsu both literally translate to English as "way or path" really meaning method. The differences is, -jitsu is more like the warriors way. Many sport martial arts these days have -do endings, and are derived from -jitsu styles. For example, the samurai practived kenjitsu, which was simply how to kill fast and furiously with the katana (and the daisho). Kendo evolved from that though sporting competitions they would hold to show off their skills, and has become an art unto itself over the years.
Jujitsu was originally the style of combat the samurai learned to defend themselfs should they become disarmed. You can't punch and kick very well while in armor, after all, but you can twist arms off pretty well. Judo eventually evolved from this combat style over time in a similar was as Kendo.
The exception (that comes to mind), is Aikido. The -jitsu derivative Aikijitsu is an offshoot of Aikido that mixes in techniques of Jujitsu.
Class dismissed =]