.wasm binaries from macOS and Linux aren't exactly the same

[MaxDesiatov]

% md5 ~/Downloads/{macos-hello.wasm,linux-hello.wasm}/hello.wasm
MD5 (/Users/maxd/Downloads/macos-hello.wasm/hello.wasm) = 719b7fd14533c95f6a0294c8d7edbe5f
MD5 (/Users/maxd/Downloads/linux-hello.wasm/hello.wasm) = a788870a0e9d370261df7dbc9a145720
% du ~/Downloads/{macos-hello.wasm,linux-hello.wasm}/hello.wasm
9.5M	/Users/maxd/Downloads/macos-hello.wasm/hello.wasm
9.4M	/Users/maxd/Downloads/linux-hello.wasm/hello.wasm
 19M	total

I don't think there should be a reason for these binaries to differ as they were compiled from exactly the same compiler source tree.