Word order withと違う


In this sentence

> その点では私は君と意見が違う (My opinion differs from yours on that point)

As I understand, the first は (その点では) is optional because it puts emphasis on
the phrase before it. The next thing is a special consturction XはYと違うwhich
means "something is different from". However, I dont understand how 意見 works
here in terms of grammar, because there is no connection between the words. Is
it better to say 私と君との意見が違う or 私の意見は君と違う?




Your sentence is perfectly natural. It can be understood as an extension of
the "double-subject" construction ( **Xは + Yが + predicate** ), which is very
common and natural in Japanese. Xは establishes the topic/scope, and Yが marks
some property that belongs to X. In other words, you can think of Yが as "in
terms of Y".

  * 私は彼より背が高い。
  * 彼女は僕より頭がいい。
  * 妻は私と性格が似ている。
  * 妹は姉と血液型が違う。
  * LとRは発音が違う。

The following sentences are also correct, but these are less common in
Japanese.

  * 私の背は彼(の背)より高い。
  * 彼女の頭は僕(の頭)よりいい。
  * 妻の性格は私(の性格)と似ている。
  * 妹の血液型は姉(の血液型)と違う。
  * Lの発音とRの発音は違う。

(The words in parentheses are usually omitted; see [this
question](https://japanese.stackexchange.com/q/77404/5010))

Likewise, in 私は君と意見が違う, 私は君と違う says "I am different from you", and 意見が marks
the "properties" of 私 and 君. 私の意見は君と違う is also perfectly correct but it's not
really better than the original. You can also say 私と君とでは意見が違う or 私と君の意見は違う,
but 私と君 **と** の意見 makes little sense (it may mean "the opinion you and I made
together" in some rare context).

