At first I thought you were referring to their resemblance as far as looks is concerned. I'm not really a fan of Yu-Gi-Oh! that's why I don't know the voice of the Japanese dubber of Yami. Anyway, I watch Bleach and I think I know Hitsuyuga's Japanese voice. I think I'll download some YuGi episodes then to be able to compare their voices.
Just the first one, season 0, will do. Don't bother after that - the ones that 4Kids licensed are (to put it politely) utter crap.
Diffrent people. In Yu-Gi-Oh! Yami Bakura was voiced by Tsutomu Kashiwakura, You Inoue and Rika Matsumoto in the diffrent seasons. In Bleach Hitsugaya Toushiro is voiced by Romi Paku.
They don't look the same for me. The hair color is different and certainly the art style is. Btw if you noticed that they look the same, have you ever noticed that most cast of Dragon Ball aside from their hairstyle is basically the same?