The first download is a MacZip'd toast image of the Mac OS 8.5 CD, as
sold in the UK. The disc contains a UK version and an International
version.
The second download is a MacZip'd toast image of the Mac OS 8.6 Update
CD, again as sold in the UK. This disc also contains a UK version and
an International version.
To perform a clean install of Mac OS 8.6, you will first need to
install 8.5 and then upgrade to 8.6. I don't think I've ever seen a
straight "Mac OS 8.6" installer.
Compatibility
Architecture: PPC
Should install on anything from a Macintosh 6100 through to early G3s,
including early iMacs with an additional system enabler.
Several features do not work in SheepShaver but do in Mac OS 9 such as
Mac OS Help.