POPO005 is used to generate the PDF for the Purchase Order and the PO_PO_EMAIL AppEngine is used to send the PDF to the supplier.
As for BIPublisher, the PO_DISPATCH program performs both functions (Creating PDF & Sending Email), thus sending the email to the Supplier. If you only want to create a PDF, change the Dispatch method to "Print" in the Add/Update PO Page.
I must not have explained it well, I am referring to the Print PO at Purchasing > Purchase Orders > Review PO Information > Print POs. We use this to print non-authorized copies for the various departments records in batch rather than having to View Printable Version one at a time and printing the individual PDFs. I have been told that with the BI Publisher version there is not this option so we would have to also customize the POPO005.sqr to try to match the BI Publisher PO_DISPATCH, POXMLP_PRINT as well as POHEADER and POLINE to try to get them to all look the same.