So, you’d like to open up two versions of an .xlsx spreadsheet to compare differences row-by-row. Seems simple, right? Just open them both up in separate windows and then arrange the two windows side-by-side. Just kidding, it’s not that easy. For some reason, Excel spreadsheets all open in the same application window, which is totally contrary to the way Microsoft Office handles Word documents. Never fear—there’s a way to compare two Excel spreadsheets side-by-side without using two computers.
Step 1
Open the first Excel spreadsheet.

Step 2
Open the second Excel spreadsheet. You’ll notice that there are now two taskbar buttons for Excel. But no matter which one you click, it pops up in the same window. Frustrating!

Step 3
In Excel, Click the View tab.

Step 4
In the Window section, Click View Side by Side. By default, this will show your two Excel spreadsheets in separate panes, stacked horizontally.

Step 5
To change the orientation, Click Arrange All. Choose Vertical to have them side-by-side, with one in a left-hand column and the other in the right-hand column.

This is how I prefer to view my spreadsheets.

Step 6
Click Synchronous Scrolling. Now, when you scroll down on one window, the other will scroll down, too, making it even easier to compare differences.

Got it? Good. Now get back to work. I need the Johnson Report on my desk by 4PM!