while Yast installer will modify xorg.conf (if i remember correctly)
nvidia installer will not, so you need to add (after installation) nvidia driver info to xorg.conf

Yast uses nvidia-installer script, so both methods listed above are comparable.
The advantage of using nvidia installer over Yast is that you can specify flags that allow installation customization. This is not listed anyway, so advantage/disadvantage of on over another is 0.