[Mike Mattera]

Gantry machine has the head mounted on a rail, supported on both side of the table. You see this in lots of routers. To to the Thermwood web site.

Nutating head or Table means that it's a 2 axis head or table, where the pivot point is at an angle. Look at Deckle Maho DMG web site for their 5 axis machines

Head/Head means that both rotary axis (on a 5 axis machine) are in the head (C & B).
Table/Table means that both rotary axis (on a 5 axis machine) are in the table (A & C).

You can also have a head/table.

Mike Mattera