Microsoft Word has as lot of features: many which the average Word-user wouldn’t have used or known about.
One of these is document comparison. You can load up two documents and see the differences between the documents. (For example, you could use it to compare the first and second draft of The Captive by copying the text into Microsoft Word, saving the documents and then compare).
Helpful instructions can be found in this article (scroll down to the heading “Compare Two Versions of the Same Document”).