to write something down means to simply write it...or put it down.Originally Posted by dodgerfan2002
-Where is my shopping list?
-On the kitchen counter. What do you need it for, mom?
-We need more laundry soap. Can you write it down for me,please, before
To write something out involves more more details, you need to elaborate more on something.
ex. The insurance company wants me to write out the account of my accident.
Before you write your English exam, write out a plan of all the ideas that come into your head.
You can also write out a check to someone.