Detect remote booting details

I have a network with remote booting machines and some of them use iPXE from their /boot partition (they use “ipxe.lkrn” from GRUB) and some of them use their BIOS built-in PXE clients.

I would like to know if there’s a way to differentiate between these methods. Can the primary boot device (e.g. an INT19 hook for the netboot ROM for the legacy BIOS) be detected somehow? Can the system tell whether the disk or the netboot ROM was used to boot the system?