Ok. So here's a scenario and you'll see quickly what this can do.
Let's say you have a chart of accounts from a few weeks ago but the accounting team are making lots of changes. They're renaming account. Adding accounts. Deleting accounts.
Many of the balances are the same, but they could also be different.
Here's what you'd like to see. You'd like a spreadsheet view that has all of the accounts. The old ones and the new ones. You'd like to see those that are unchanged line up so they're side by side. So if account 1010 Cash has $1000 before and after, they just line up.
You'd like to see empty space in the original chart of accounts if the new accounts don't match the old ones. You'd like to see empty spaces on the new side if an old account was deleted.
You'll see in the images below how Row by Row differs from Cell by Cell. Also, you'll see how to adjust the number of Key Columns.