These numbers matched exactly to what is currently in the AppStore for the last release we have ready for sale
Is that what you are doing?
Because otherwise, it includes the bitcode size. (i don't pretend this makes sense. only that it is :P)
In any case, i would still bet more heavily on it being displayed wrong than anything else.
If i was to increase the binary size of first party apps at google by even 1%, there would be a mob with pitchforks at my desk in less than an hour.
I can't imagine apple is really different.
Between the org and culture differences I'm just not so sure Apple can be safely assumed as similar as you expect.