zypper Smarter than YaST?

For some reason, even though both use libzypp, zypper seems to resolve problems better than YaST.

E.g. I finally decided not to upgrade to compiz-fusion git, But I wanted at least 0.7.6, so I added, the X11:XGL Repo, I tried to install the compiz-fusion-gnome metapackge, and it ended up pulling many i586 packages instead of x86_64 (which did exist!), and it didn’t upgrade compiz/-gnome either, however doing this from zypper gave me the proper result, compiz fusion 0.7.6 perfectly working from x86_64 packages

Anyone else see this?

[offtopic]What’s the difference between ‘zypper dup’ and ‘zypper up’? I know that zypper dup upgrades the OS, but in terms of ‘what-they-do’ ?[/offtopic]