Differences between standard and rescue kernels

[Alex Regan]

Hi,

I installed fedora21 on an AMD x86_64 box then moved it to an Intel 
x86_64 box and it would no longer boot. It would get to the following:

Switched to clocksource tsc

then just sit there. Booting from the rescue kernel worked properly.

What is the difference between the standard default kernel and the 
rescue kernel?

# grep ^menuentry /etc/grub2.cfg
menuentry 'Fedora, with Linux 3.19.7-200.fc21.x86_64' --class fedora 
--class gnu-linux --class gnu --class os --unrestricted
..
menuentry 'Fedora, with Linux 0-rescue-1b5a0c2dfaca499c98f601585417d143' 
--class fedora --class gnu-linux --class gnu --class os --unrestricted 
$menuentry_id_option 
'gnulinux-0-rescue-1b5a0c2dfaca499c98f601585417d143-advanced-a76c8f65-ff02-470b-b087-453fc8b6275e'

Also, what is this new initrd16 and linux16 grub2 options?

Do I need to rebuild the initrd to support the AMD processor on the new 
machine? I believe I use dracut for that?

Thanks,
Alex