What is the difference in the role of an operator and the role of a promoter?

A promoter is found upstream of all genes and is the site where RNA polymerase binds for transcription to begin. An operator is again a nucleotide sequence but is found only in operons and regulons. The operator region, depending on a cell's regulatory mechanisms, is where an activator and repressor bind to either turn on or off transcription                              

This is a time line from 685 to 978