extra megabytes

[timelessbeing]

I used Superduper to clone one external HD to another. After completion, I clicked "Get Info" for the two volumes. The source says Used: 989.77 GB on disk (989,768,949,760 bytes) and the destination says Used: 989.98 GB on disk (989,975,355,392 bytes). The target HD was erased before the procedure. I compared the Get Info windows for each subfolder on each HD and they exactly matched.

What is the extra 206,422,016 bytes I am seeing? Some kind of file system overhead?

 

[simsaladimbamba]

That is the partition map and some extra and important information.
Here is how it looks in Disk Utility with my 1.5TB HDD in 10.6.8.

 

[timelessbeing]

Both HDs only have one partition. However, one has a GPT and the other has a APM. GPTs are larger? Or is it because the HD is twice as large as the other?