remote X vrs VNC

While I realize VNC can be used on multiple os's, I saw a snip of an article that POed me. It claimed that you couldn't graphically remotely administer a Linux machine before VNC. I assume it was a newbie (as am I), but one who didn't know about X, or Webmin, and came from a PC Anywhere background. I have used VNC at my brothers, but haven't messed with x remotely; what are the benefits/limitations of either, relating to a Linux installation. Has anyone messed with X remotely going either way from a X.org machine to Xfree or vice versa. Trying to learn from others mistakes before I fiddle TIA Randal