What is different about the Bujinkan?

What sets the Bujinkan apart from other modern cognate forms of martial training (Karate, Kendo, Judo, Aikido, etc.) is that the techniques which are still studied today were formed on the battlefields of Japan before nationwide peace was achieved by the Tokugawa Shogunate in 1603. During the 250 years of peace that followed, the warrior class, their skills no longer needed on the battlefield, began to turn to more humanitarian endeavors. The martial arts that were founded during this time of peace hold perfection of character as more important than combat effectiveness.

The Bujinkan is unique in that combat effectiveness is still held at the highest level, techniques not being diluted to accommodate safety. This means that there is no tournament competition, as techniques are studied for real-life situations only.

Particpants generally practice with a partner, taking turns performing the role of uke (receiver of a technique). The instructor will typically demonstrate a basic technique (kihon) with an uke at the beginning of class, and the students will pair up and attempt the technique just shown. As the class progresses, numerous henka (variations) of the kihon will be shown.

It is this limitless world of variations that the student is expected to enter so that he can spontaneously create a technique from nothing should the need arise, as real-life situations rarely play themselves out as a kata shown in class.

Source: http://www.hemelbudo.org.uk/Articles/Bujinkan.pdf