[scribus] b/w document: PDF greyscale or printer?

[vwf]

Hello,

I'm nearing completion of a book, and trying to get the details right.
The inside is b/w, with many photo's. I can export to PDF greyscale or
printer. To me both are the same, but the output is very different. Is
there a document that explains the differences and needs to be done for
optimal results?

The cover is in full colour (with spot-colours). The spot colours will
probable need to be converted into process-colours, but the problem is
the colour profile for the photo. Do I need to select a colour-profile
in the PDF output? I added a colour profile to the image itself.

Thank you,

Frits