Does it exist some component for displaying differences between versions of Word document inside SharePoint?
It is possible (https://support.office.com/en-us/article/Compare-versions-of-a-Word-document-in-a-document-library-b4b1a33f-8726-4516-87de-533da7f5edf3), but I don't believe it is possible OOTB (though I could be wrong).
The easiest option, if you can't compare two documents in SharePoint, would be to use the Compare feature in Microsoft Word (offline). That will show you the differences between to documents. To do this, just select the Review tab in the ribbon and click Compare.