Hi all!

I would like to ask you for some advice about the "Zypper Updater".

When I do a "zypper update" I get:

Code:
zypper update
Loading repository data...
Reading installed packages...
Nothing to do.

but when I do a "zypper dup" I get:

Code:
zypper dup
Loading repository data...
Reading installed packages...
Computing distribution upgrade...

The following packages are going to be upgraded:
  gstreamer-0_10-schroedinger gstreamer-0_10-utils gstreamer-utils hplip hplip-hpijs 
ktoblzcheck libofx4 libschroedinger-1_0-0 libtheora0 sox tightvnc xsane 


The following NEW packages are going to be installed:
  blt gamin gstreamer-0_10-fluendo-mp3 inkscape-extensions-fig 
inkscape-extensions-skencil libcaca0 libktoblzcheck1 libltdl3 liboil-0_3-0 
libquicktime0 libsndfile1 python-imaging python-lcms python-tk sk1 sndfile tix transfig 


The following packages are going to be reinstalled:
  apparmor-profiles apparmor-utils compiz-manager desktop-data-openSUSE docbook_4 
glib2-branding-openSUSE glibc-i18ndata glibc-locale iso_ent liberation-fonts nscd 
openSUSE-build-key pciutils-ids pm-profiler polkit-default-privs 
sound-theme-freedesktop suseRegister update-alternatives xmlcharent yast2-apparmor 
yast2-backup yast2-branding-openSUSE yast2-firewall yast2-inetd yast2-installation 
yast2-iscsi-client yast2-registration yast2-registration-branding-openSUSE 
yast2-samba-server yast2-sudo yast2-theme-openSUSE 


The following packages are going to be REMOVED:
  fam gst-fluendo-mp3 libcaca liboil libquicktime libsndfile 


The following packages are going to change architecture:
  glibc-i18ndata glibc-locale nscd 


The following packages are going to change vendor:
  gstreamer-0_10-schroedinger gstreamer-0_10-utils gstreamer-utils hplip hplip-hpijs 
ktoblzcheck libofx4 libschroedinger-1_0-0 libtheora0 sox tightvnc xsane 


Overall download size: 43.9 M. After the operation, additional 44.0 M will be used.
Why is that?
I use the same Repos when I do a "zypper update" and the update is sometimes just a minor jump like:

tor-0.2.0.33-0.pm.1 >> tor-0.2.0.34-0.pm.1

I would understand if I added the OpenOffice Build Service Reop
and then the upgrade is done via "zypper dup"

And why some packages change the architecture when I use "zypper dup"?

And last bust no least:

Is it advisable to do "zypper dup"?
Will it affect the stability of my system?

Thank you very much for your answers,

Claus