When I’m working with git, I like to compare files at the commit level. You have version X displayed in the left window, version Y in the right window, and any differences in the two versions are shown in color - extra changes are shown in green, and missing changes are shown in red. On one of my last projects I needed to compare changes in a .sql script that was not available in SSDT, but only in SSMS.
In my recent project I ran into situation, where I had to turn off page compression on some of the indexes. Unfortunately, indexes were dropped and re-created in stored procedures, so I had to identify those procedures and change the data_compression setting from PAGE to NONE.
To do this I’ve decided to query sys.sql_modules DMV and check the definition column, which contains stored procedure text. I just copied text into clipboard and then pasted into new query windows and … no voilà effect :-(.