Truncated cheque: A cheque whose physical movement is stopped and an electronic image is sent for processing instead.

Electronic cheque: A digital version of a cheque created, signed, and processed electronically without a paper form.

Truncated cheques are physical cheques that are converted into a digital image during the clearing process. The physical movement of the cheque is stopped (truncated) and only the electronic image is used for processing, which speeds up the clearing system.
Electronic cheques are cheques that are created, signed, and processed entirely in digital form using secure digital signatures. These do not exist in paper form at all and are transmitted electronically from the drawer to the drawee bank.
Both types aim to enhance efficiency and security in cheque transactions.