Well not really - if a Japanese speaker write a word to another Japanese speaker they could conceivably write the word out through either of these alphabets - t

Well not really - if a Japanese speaker write a word to another Japanese speaker they could conceivably write the word out through either of these alphabets - they're mutually understood and they are able to perfectly (iirc) represent all of the words used in the language. I don't think anyone would suggest that it's possible to do this with Chinese and Cyrillic characters. I actually think you'd be the first to suggest this is the same thing. I'm really confused why you'd say this.