The Score Comparison Tool allows you to compare two versions of a score to find the differences between them.
You open the tool from View→Score Comparison
The dialog have three sections. To the left you select the scores you want to compare. In the middle section, you select how to view the comparison, and to the right the result of the comparison is displayed.
First step is to select the score. Use the combo box next to "Score 1" to choose between the currently open scores, or use the Browse button to open the File Explorer and select a score from disk. Next use the combo box to choose if you wish the first score to be the current version, or the last saved version.
Score 2 will be set to the same score, you selected for Score 1, but you may choose another of the open scores.
When you have selected the scores and versions press Compare to do the comparison.
By default the Intelligent comparison is selected, which will display the differences in human-readable format (eg, "Measure 1: Note: property pitch changed from B4 to C5").
Change the selection to Raw if you prefer to see the results according to the actual XML code.
When you press Compare a list of differences will be displayed to the right, and the score view will automatically change to Documents Side by Side, with the two scores you have selected displayed within.
Double-click on a difference from the list and both score views will automatically pan to show you the changed element, which will also be highlighted.
Below you will see two small scores with a few differences between them.
The result of the comparison will look like this: