I'm compiling a collection of all Mac OS X installers ever released. I recently hit a roadblock when I found that my Snow Leopard build 10A432 ISO matched some checksums online, but not others.
So, I downloaded a second ISO, which matched the checksums the original ISO did not. This was a bit concerning, so I recursively compared the files of each DVD with Meld. One, single file was different.
/Instructions.localized/Installation Instructions.app/Contents/Resources/French.lproj/Instructions d’installation.pdf
This is the French translation of the Mac OS X installation manual. It turns out, one DVD still had the 10.5 Leopard variation, while the other had the 10.6 Snow Leopard variation. I guess somebody at Apple was fired on Snow Leopard's launch day.
Checksums of ISO with 10.5 Leopard "Instructions d'installation.pdf":
MD5: 8bce5139afaaa5a8fcda213edf5202b1
SHA-1: 41eca20763eb74c3e23f0bebc36095520e187dc1
Checksums of ISO with 10.6 Snow Leopard "Instructions d'installation.pdf":
MD5: e26826cc68281aa581cc181483bd232d
SHA-1: 0b6435228ddd9f39955c6b3f196d65dec17c2dfd