ActionScript _parent

After sometime i finally understand “_root” and “this” in actionscripts.
I was wondering can some one tell me is this correct about _parent.

Example: apple movie clip is inside orange movieclip

so for _root, the script goes like this: _root.orange.apple
so for _parent also like this: _parent._parent.apple

Is it correct?

If it correct…wat the different since both still work…@_@
if wrong.can you correct me…

Thx