If you have versioning enabled in SharePoint against your document library you can track and restore previous versions. It wont tell you precisely what has changed, but will allow you to see who and when a new version was saved. Attached is an image showing one of my Word documents version history
Click here for the Microsoft support article on version history of items in a list of library
To see what parts of document has changed you have to open document in regular Word (expand Edit menu for this) then you can enable Track changes and see changes. Teams internal viewer/editor doesn't show it.