The "old" interface provides the same facilities and behaviour as was in place last year. It should be regarded as the default for teaching. If no specific choice is made, the terminals will use this interface.
The "new" interface provides an interface that is in most respects identical to the "CUED on a cdrom" system. It is intended to migrate teaching material to work under this interface (in most cases, this need not involve significant change, although handouts that describe details of the user interface may need slight change). A small number of practicals run this academic year will do so under the "new" interface.