To open two tabs in the same document and compare:

Step 1: Once you have the document open, click on the “View” option.

Step 2: In the “Window” grouping, click on “New Window”.

Step 3: Right next to that, click “Arrange All”.

Step 4: Check the boxes for “Vertical” and “Windows of active workbook”.

To open two different documents and compare:

Step 1: Once both documents are open, click on the “View” option.

Step 2: In the “Window” grouping, click “View Side by Side.”

To scroll in both windows at the same time:

Step 1: In the “Window” grouping, click on “View Side by Side”

Step 2: Right below that, click on “Synchronous Scrolling”