Electrodeionization (EDI) and Continuous Electrodeionization (CEDI) mean the same thing. By its very nature electrodeionization is a continuous process, therefore the Continuous in the CEDI is redundant.
CEDI and CDI are just marketing terms.
Although the different stack/module manufacturers have different designs and configurations, the fundamental operational principals are the same. All EDI stacks/modules use electrical current to continuously regenerate resin within the stack/module. When water comes into contact with the electrical current, it breaks apart to form 1 H+ molecule and 1 OH- molecule. These molecules are the active ingredients required to regenerate the anion and cation resin within the EDI stack/module. Therefore, to ensure the highest quality of water the EDI stack/module needs to have electrical current applied across it continuously when it is in operation. In addition to regenerating the resin within the stack/module, the electrical current also allows for the migration of the contaminant ions out of the product stream and into the concentrate stream.
NOTE: DO NOT APPLY ELECTRICAL CURRENT TO THE STACK/MODULE WHEN THERE IS NO WATER FLOWING THROUGH IT