I have no idea why they might differ, it should be being sourced from the same address/url. The on-line installation file is a stub installer and I don’t know if the server would be checking what version you might need. For example those with XP/Vista can only get avast 18.8 (maximum).
Personally I would always use the off-line installation file and save a copy of it for use on, another computer or in the future.
You should check the digital signature of the file (via file’s properties) - if there’s an Avast Software digital signature and is valid, then the file is legit.
Thanks for your prompt response David. No I did not download the file from either of those operating systems.
Thanks Igor. One does seem to, and checking the other one now.
I am honestly concerned as to why there are two different files with the same name. Do different countries have a different list of mirrors in the installer?
Mystery may lie in the fact that both systems are identical and the operating systems are the same, hence why are the MD5’s different when the downloaded file is for the same exact program on both systems?