yum vs. yast

I'm in a rather large environment and have to support red hat as well as suse. I'm already running yum on red hat and would prefer to do the same on suse. I have it running, however I want to make sure performing a yum update of a service pack will achieve the same results as using yast. For example, when I used yum to install sp2 on sles9, I first had to yum install kernel-source, then yum update?