There's a big difference: while Hungarians employ the Roman alphabet, making the spelling of Rózsa, or anything else Hungarian, immutable for other tongues that use the Roman alphabet (accent marks notwithstanding), "Miyuzumi" is a transliteration from the Japanese alphabet. The ultimate purpose of transliterations is to provide, as close as possible, the phonetic values of the original language. As such, the standards of transliteration from one alphabet into another are inevitably somewhat fluid, varying as they do from country to country.