* Different Chinese variations (Cantonese, Min, etc.) have different readings. Initials, vowels, and finals all differ.
* When borrowed into Japanese, the Chinese initial was ŋ, which isn't used as an initial in Japanese, and was substituted.
I also wouldn't assume that sounds that are grouped together are supposed to sound the same. en/yin/wen/yun use the same final in bopomofo, but sound different.
https://en.wiktionary.org/wiki/%E6%BA%90
Some highlights:
* Different Chinese variations (Cantonese, Min, etc.) have different readings. Initials, vowels, and finals all differ.
* When borrowed into Japanese, the Chinese initial was ŋ, which isn't used as an initial in Japanese, and was substituted.
I also wouldn't assume that sounds that are grouped together are supposed to sound the same. en/yin/wen/yun use the same final in bopomofo, but sound different.