I'm confused by the difference between 'build.sh build'
and 'build.sh distribution '.

=46rom /usr/src/BUILDING, I read:
  build         Build the entire NetBSD system
  distribution  Do a ``make build'', and then install a full distribution
                     into DESTDIR, including files in DESTDIR/dev, =09
                     DESTDIR/etc, DESTDIR/root and DESTDIR/var.

=46rom http://www.netbsd.org/Documentation/current/ I see that:

1) if I want to update kernel+userland, I must
    - 'build.sh distribution'
    - 'build.sh kernel'
    - install new kernel
    - reboot
    - 'build.sh install' the distribution

2) if I want to update userland only, I can (must?)
    - 'build.sh build'
    - 'build.sh install' the new userland

Is this the installation of the new kernel in situation 1
that requires 'build.sh distribution' instead of 'build.sh build'?
What if I 'build.sh build' instead of 'build.sh distribution'
in situation 1?
What are the additional steps performed by 'build.sh distribution'
which allow installation of a new kernel between building
and installing userland? Population of /dev /etc and /var ?

Regards,
Thierry.