What is difference between /etc/rc called programs and ones called after login prompt shows up

[Aryeh Friedman]

What is difference between /etc/rc.d called programs and ones called
after login prompt shows up?

The reason for asking is sysutils/fusefs-kmod gives an error if any
mounts are attempted in /etc/rc but if the exactly the same command is
issued by a user's .login/.xsession/etc. it works without problem
(assuming proper permissions of course).

a) Can anyone think of a reason why this would happen (the maintainer
is non-responive)
b) Is it possible to force something to run after /etc/rc exits but
before init calls getty?