Caranthir actually looks quite similar to Feanor as well. While doesn’t look like a near clone like Curufin, he surpasses him in height by an inch, unlike Curufin who is somewhat shorter. Where Feanor and Curufin have dark brown hair, Caranthir’s is jet black – but besides that it is identical to his father’s in texture and length. Where Curufin’s features are sleeker, Caranthir’s are less so and more sharp and “masculine”. Caranthir also inherited Mahtan and Nerdanel’s slightly ruddy complexion. But these are their only differences, and besides these things Caranthir looks quite like Feanor. He inherited the same wide shoulders despite not being a smith, his height, hair, eyes, general facial structure, skin tone, his piercing gaze.
He is much, much more like his father in mind than Curufin, though, which people never noticed. Curufin was much less haughty and more deceptive and secretive than their father, he was keener and knew better to keep his thoughts to himself. When Feanor was loud, Curufin was quiet. Curufin was like a snake while Feanor was like a lion. What Curufin took after Feanor in was purely his physical looks and abilities – and pride, perhaps.
But Caranthir took on Feanor’s intelligence. Some may say he surpassed it, even. He took on his linguistic abilities, strategic abilities, mathematic abilities, political abilities – yet also of course his temper, rashness, and suspicion. Only he was smarter when it came to mathematics and politics, and eventually perhaps even linguistics – but that may have been because Feanor never had the chance to learn dwarven and mannish languages. Caranthir is a clone of Feanor when it comes to matters of the mind as Curufin is a clone when it comes to matters of physicality.