Solution
As now, there is no built-in tool in LabVIEW allowing to compare two different project files.
The only possible workarounds could be:
- compare the two .lvprj files, by opening them with a text editor, since the LabVIEW project file is essentially an xml file
- compare the hierarchies of the main VIs of the two projects by selecting Tools » Compare » Compare VI Hierarchies
- compare VIs by selecting Tools » Compare » Compare VIs
- integrate a source code control provider in LabVIEW
The last three options, however, would allow to compare VIs and not other project items, such as non-LabVIEW files, build specifications, libraries etc.