Well, they have a similar purpose, but knights strive on protecting women and noble children while samurai would say that they have the capability to protect themselves. The samurai usually used a long sword (katana) and short sword (wakizashi). Together they are the daisho. The knight usually uses a sword and a shield. A knight would be allowed to surrender and be held for ransom while a samurai is supposed to commit suicide. However, a similarity for both classes will be the fact that few of their class will live to what they call "honor".
