There is some truth to “not all linux is the same linux under the covers”. SUSE uses different library paths than RH for some shared libraries and shared object files. But that only affects developers/installation developers, not the sys admin usually unless they’re writing c/c++ code and compiling it for multi-linux-OS’.
Based on slow’s answer, I’d say pick one and start hacking on it to learn. If you have any questions, post’em up. There’s got to be more than one linux operator/sysadmin on this board that would be willing to help.