What I know (please correct if my understanding is wrong):
vmlinuz: is a compressed, self-extracting, bootable Linux image. Always ELF? Generated how?
zImage (or bzImage): are compressed, self-extracting, bootable Linux image. Always binary. Generated by “make zImage” .
but it doesn't look so. I have build embedded Openwrt project and got this info when doing "file vmlinuz":
vmlinuz: ELF 32-bit MSB executable, MIPS, MIPS32 rel2 version 1 (SYSV), statically linked, stripped
as can be seen it is in ELF format and NOT a binary as zImage.
to add to confusion, when I do readelf on my ubuntu vmlinuz, I get that it is not an ELF file.