Difference Viewer
TeamCity Difference Viewer allows to review the differences between two versions of a modified file and navigate between these differences. You can access it from almost any place in TeamCity's UI where the changes lists appear, for example, Projects page, Build Configuration Home Page, or Changes tab of the Build Results Home Page and so on.
After you click the modified file name, a new window opens:
The window heading displays the file modifications summary:
file name alone with its status,
changes author,
comment for the changes list.
To move between changes, use the next and previous change buttons and red and green bars on the versions separator.
If you want to switch to your IDE and digg into the issue deeper, click the Open in the IDE button in the upper-right corner of the window. The file in question opens, and you will navigate to this particular change.