Hey Andy,
I also use Git and can only praise its enormous usefulness, not only for writing and managing code, but also for texts or writing of any purpose. The same applies to the diffs, with which the differences between texts are displayed in color so differences can be seen at first glance. Git was created by Linus Torvalds for managing the Linux kernel source code, but it is used for thousands of other projects today. I described git → in this post the other day.
There are also diffs outside of Git, e.g. the forum software we use here uses Markdown language which supports Unified Diff syntax highlighting:
Here I have a text.
- I have not changed it.
+ I have changed it after all.
That looks pretty good.