View differences of content in files with same name

[wirwifireless]

When there are differences between left and right files with same name,
It allows to show differences about content in new view, left and right file with number lines, and mark any colours to show these differences.

[bgstack15]

This sounds like a generic "diff" mechanism available in GNU/Linux by default, or Notepad++ "compare" view. I don't think FreeFileSync has such a feature, but I think such a feature could be added to invoke another program.
Perhaps this could be implemented with a context menu entry, and the entry could be configurable and use variables like:

notepad++ --comparison $left $right


Or similar syntax. I'm not sure if Notepad++ has any specific mechanism for opening it immediately to compare view, especially considering the comparison view I am thinking of is from a plugin.
For example, I would like to use:

diff -aur $left $right


[Zenju]

https://freefilesync.org/manual.php?topic=external-applications