external back up drive space question

[dollface14]

My back up drive says I have 9GB free when I look at icon on my desktop- but when I click on the icon to get more info it says I have 178.29 GB available. Is there a difference between available and free? I want to download a 7 GB movie I made to it and don't understand if I will have 2 GB space left afterward to store things or much more.

 

[digitaldoc]

Available and free should be the same. I would look in "My Computer" and the drives will tell you how much is filled from the total.