Int & Ext HD using the same amt. space?

So I took the HD out of my old MacBook, put it in a case, connected it to my New MacBook Pro, and migrated everything to the new laptop. Then I erased the old HD, and moved my Pictures and Movies folders to it. Then I erased those 2 folders from the new laptop.

I question is, the external HD and the internal HD both show that they are using 130GB. How can that be? The external HD only has 2 folders on it. Whereas the internal HD has a lot ore folders like: Applications, Downloads, Music, and the OS.

On the Internal HD the folders are: Downloads = 13GB, Music = 33 GB, Documents = 3 GB, Applications = 12 GB,

On the External HD the folders are: Movies = 27 GB, Pictures = 100 GB.