You Release a Mortgage or Charge when the property charged has been released from the charge or no longer forms part of the company's property.

You Satisfy a Mortgage or Charge when the debt of the charge has been paid or satisfied in full or part. 

Note: By filing form MR04 (denoted FULL) you will not remove the charge from the company record; however, the status of the charge will be shown as FULLY SATISFIED.