It is true for lots of characters (so I guess I was being a little hyperbolic when I said "all"), and you cannot rely on choosing the correct code points in order to have a text display Japanese or Chinese. You need to tell your rendering program (often through choice of font) if things are to be rendered with Japanese or Chinese forms.
I wouldn't know how to show you examples here, as 直 will 直 display the same since they have the same code point, but different number of strokes in japabese and chinese.
Aren't they putting the disunified characters into the U+2xxxx plane now?
Han unification is generally seen as a bad choice in retrospect, but it was something Unicode had to do when it looked like 2^16 codepoints were all they were going to get.
Never heard of that, but I would appreciate if all the characters with different glyphs had different codepoints. Do you have a source? Do you know what happens to the "unified" code-points?
I wouldn't know how to show you examples here, as 直 will 直 display the same since they have the same code point, but different number of strokes in japabese and chinese.
https://en.m.wikipedia.org/wiki/Han_unification