I believe Dispatch Release is where an aircraft flight plans to destination A and with enough fuel to reach that destination legally. Subject to many factors including winds aloft, fuel burns, and other "issues". If enough fuel remains after a certain time the aircraft may be "re-released" to destination B which is the original destination. The Captain is ultimately responsible for Dispatch release as he/she is the pilot-in-command. It was/is used by predominately US carriers, however I stand to be corrected.