difference between initrd and initramfs
 

What are the differences between initrd and initramfs?

I used gentoo genkernel to make a kernel, and it only put an initrd file in /boot.

It modified grub to point at an initramfs file.

Not a lot. Different version of the same thing, Grub will support both but not two at the same time for obvious reasons. I've heard initramfs has a few more features than initrd but I'm not an expert, my kernel packages come with a script that generates a new initramfs image with my modules, gensplash and everything else :D I love Arch lol