Difference between "Bytes In" and "Content Breakdown"

[it2LCN]

Hi everyone,

It's my first time here and I conducted a test for a page I am developing, you can see it here:

http://www.webpagetest.org/result/151007...ls/cached/

My question is: in the "Repeat View", there are 115KB "Byte in" for the fully loaded document, while the sum of the elements on the content breakdown is barely 35KB.
Excuse me if this has an obvious answer as it is my first time here but, why that difference? Which are those Bytes which are not qualified as content?

Thanks!!