xrdp under centos7, which session type do I need to try? xvnc or xorg?

Question

I just enabled the Xrdp service under a new installed centos7 system.

When I use the Windows remote desktop client(mstsc.exe) to connect to the xrdp server, I see there is an option which can let me choose a session type, see the image show below: So, I have tried both types. First, I try the xvnc(the tigervnc server install when I install the xrdp), I see that when I open the firefox, I see that the tab bar has some blue colors, and when I right click on the link, the context menu shows badly, see the image shot below:

Second, I try the xorg option, the firefox shows correctly, see the image shot below:

So, my question is: which is better? It looks like xorg shows correct color. But when I search the internet, I see some webpage says the xvnc is faster, see this page: Why is VNC so much faster than X Forwarding (both tunneled)? - Ars Technica OpenForum or Xvnc faster (less laggy) than x11rdp/Xorg drivers · Issue #386 · neutrinolabs/xrdp. Some web says vnc just mirror the images, while xorg mirrors the drawing vectors, so xorg may be better.

In this page xrdp, there is another term: X11rdp. So, I'm totally confused. Any one can give me the suggestions?