To do that, Inkscape would either have to store change history inside the SVG file, or have some means of selecting two files at once.
To my knowledge, it has neither of those things, so it would probably not be a trivial thing to implement.
For your own reference, you could create a layer in your inkscape document called "changed" and fill that layer only with red-outlined polygons (rectangles would work in most instances), highlighting waht was changed since the last version of the file was opened. You'd have to do that manually.
It's also a question of what constitutes a "change" in the svg file. A relatively simple change in grouping/breaking apart/regrouping can almost completely re-write the svg file, and look nearly the same. :)
It would be interesting to know your use case though. How would this feature make your work easier?
-C