Help understanding the usage of 「で」 in this clause


I get the gist of this answer, but I fear I might be misunderstanding the very
last part of the second sentence:

> 「今週末」と同じ意味なのは「今度の週末」じゃなくて「今週の週末」かな。
>
> 今度の週末は次の週末と同じ意味で、日曜日では「今度の週末」は「来週末」 **のことで「今週末」「今週の週末」とは** 違う日を指す。

My understanding is this:

> "This weekend" doesn't have the same meaning as "this time's weekend" but
> instead "this week's weekend".
>
> 'This time's weekend' is the same as 'next weekend', and on Sunday, [the
> idea of] "this time's weekend" is the same as "next week's weekend", so it
> is different from "this weekend" and "this week's weekend" because they
> refer to different days.




> 今度の週末は次の週末と同じ意味 **で** 、日曜日では「今度の週末」は「来週末」のこと **で** 「今週末」「今週の週末」とは違う日を指す。

The two で's are both the てform (or the continuative form/連用形) of the copula
(or the assertive auxiliary) 「だ」. The で's here basically mean "... is ~~,
and". So this sentence can be split into three clauses like this:

>   1. 今度の週末は次の週末と同じ意味だ。
>   2. そして、 日曜日では「今度の週末」は「来週末」のことだ。
>   3. そして、(日曜日では「今度の週末」は)「今週末」「今週の週末」とは違う日を指す。
>

which would respectively translate to:

>   1. 今度の週末(this/next/coming weekend) has the same meaning as 次の週末(next
> weekend).
>   2. And, on Sunday, 今度の週末(this/next/coming weekend) refers to 来週末(end of
> next week).
>   3. And, (on Sunday, 今度の週末(this/next/coming weekend)) refers to a different
> day from 今週末(end of this week) or 今週の週末(weekend of this week).
>

(#2 and #3 share the same subject.)

* * *

「～～と(は)違う」 means "to be different from ~~". So #3 literally means:

> 「今度の週末」は、（「今週末」「今週の週末」とは違う）日を指す。  
>  今度の週末 refers to a day (which is different from 今週末 or 今週の週末).

「今週末」「今週の週末」とは違う is a relative clause modifying the noun 日.

* * *

By the way, by the first sentence they're saying...

> 「今週末」と同じ意味なのは「今度の週末」じゃなくて「今週の週末」かな。  
>  今週末(end of this week) has the same meaning as 今週の週末(weekend of this week),
> rather than 今度の週末(this/next/coming weekend), I think.

(They're trying to say 今週末 is [今週]{this week}+[末]{end}, not
[今]{this}+[週末]{weekend}.)

