They obviously were both highly accomplished swordsmen and know for their ability to deal death at the end of a blade, be it a short or long blade. The knights however were grandiose and known for the showmanship and presence of their status with horse and Armour. The samurai while quite similar did not wear Armour and if any protection it was more in the form of bamboo guards and protection with their silk and fancy robes. The knights of course wore Armour that differed with the country and times as did their steed and the page was available to provide a change in weaponry. The samurai were known more for their stealth, cunning and having the ability of going unnoticed and detected and more of a magical never really being their and walking on water and other impossible feats. This is why they were also not viewed as perhaps as capable by Europeans and other non-Asian's as they deemed the sneaking and stealth as an inability to wield their weapons in open battle with much bravado, which of course was not true or accurate.
Knights are european and samurai are japanese. They both wore armor rode horse back and had a code of armor
Both knights and samurai were warriors