difference between updateDisplaylist() and CommitProperties(

Commitproperties =>*commitProperties() processes the properties set on the component. You do not call this method directly. Flex calls the commitProperties() method when you use the addChild() method to add a component to a container,or when you call the invalidateProperties() method of the component. Calls to the commitProperties() method occur before calls to the measure() method. This lets you set property values that might be used by the measure() method.*

updateDisplayList => *The **updateDisplayList() method sizes and positions the children of your component based on all previous property and style settings,and draws any skins or graphic elements that the component uses. The parent container for the component determines the size of the component itself. *