Flex: Item Renderer v/s Item Editor

Item renderer only renders the particular row/column. The item in this case is read-only. It is always present in all controls.
However Item Editor allows you to display and make the item editable.

   1:  <mx:DataGridColumn dataField="vacationEligibility"

   2:      headerText="Vacation Days">

   3:          <mx:itemRenderer>

   4:              <fx:Component>

   5:                  <mx:Box>

   6:                       <mx:NumericStepper minimum="2" maximum="26" 

   7:                           stepSize="2"/>

   8:                       </mx:Box>

   9:               </fx:Component>

  10:          </mx:itemRenderer>

  11:  </mx:DataGridColumn>