List only kernel processes (by listing kthreadd and it's child processes)

ps --ppid 2 -p 2
ps --ppid 2 -p 2 -F

List only non-kernel processes (by excluding kthreadd and it's child processes)

ps --ppid 2 -p 2 --deselect
ps --ppid 2 -p 2 --deselect -F
ps --ppid 2 -p 2 --deselect | sort -k 4