qgis - How to see what lines have changed in an updated Shapefile?

I'm using my county's GIS data to update the roads in OpenStreetMap. I have a copy they published last year and one that was just published, and I'd like to find all the LineStrings that have either had their attributes or their geometry changed. This will assist me in making sure all the new and modified streets are updated in OpenStreetMap.

I'd like to do this using FOSS software, such as QGIS or Python/OGR. The street segments should have a unique identifier, so my only thought is to write a Python script which opens both Shapefiles, finds any segments in the new that aren't present in the old (added segments), and the reverse (removed segments), and then loop over matched pairs comparing their constituent coordinates to see if anything has changed.

Is this a good approach? Is there a simpler way?