He is similar in presentation to Piccolo in that they are both serious, green-skinned and wear weighted clothing. He is very strong and at least equal in strength to Goku in his maxed Super Saiyan form that he used against Perfect Cell. In addition to his great strength, and most notably his speed, he has powerful techniques, including an "Omega Mode" that is similar to Goku's Kaio-ken, in that it provides a brief but incredible boost to energy, speed, and strength. He is able to create Dragon Balls and had granted Shenron with some new powers.
When Kor is introduced, he appears roughly the same as Piccolo, but with a more solid facial structure, as well as slightly thinner and a bit shorter. As the series went on Kor's outfit became more his own, and by the time he faced Reiten his gi lost whatever blue was in its color and gained more of a purple one, and his neckline became more low-cut like Goku's outfit.