Export or print to pdf better?

which one is better to lose/remove metadata of photos in document, print or export to pdf?

please do not suggest to remove metadata before putting in document i already did it. i am asking this for my learning

also, when i export i do not see an option for grayscale… .is there none?

for info, this is for the book i will self publish in grayscale…

I’d say I expect less available data in print to pdf, but BOTH are not designed to remove metadata from images. So you have to test the result. Also: Print to pdf is not controlled completly by LO, so expect different behaviour for different printer-drivers…
.

This is a typical option of printer-drivers, to save on colour-ink or because a printer supports only black/gray. But pdf supports colour…

With print you can use the option
image