Normally I would expect a date and/or meta data to vary slightly even between builds on the same host.
You also neglected to mention compiler flags, (optimization and #define
s from the command line for example).
I would however initially suspect the files should come out to the same size, which leads us to the conclusion that something is not the same across the two systems. The most likely candidates are system headers (just one root-level feature in the OS install could cause an entirely different view of these files) and any dependent libraries.
You can check that the headers are the same by preprocessing with g++ -E
or similar. You can also follow the library path and confirm that the linked-to files are identical on each system.