ClusTerm is used to SSH into a cluster of systems and execute the same command on all the systems. It combines a number of Gnome Terminal Widgets (VTE) in a single graphical window and copies the input to one terminal to all other terminals. It shows the differences between different terminals. Different layouts: table, row, column, and notebook. It is a GNOME application based on libvte.
Multixterm creates multiple xterms that can be driven together or separately. It can be used to login via SSH to multiple hosts and control them simultaneously, or for ad hoc things where you want to see the results as you type. Each xterm may also be driven separately. Multixterm is scriptable so that you can easily fire up, for example, a dozen xterms with a single command, tiled nicely on your screen. In addition to SSH, multixterm can drive rlogin, telnet, passwd, or any program that runs in an xterm.