I suggest you do not "generalize" among 747 freighters.
Used to fly 747-200/300s... There were differences with 747 freighters.
Those known as "747-xxxF" which were "real freighters".
And those converted from passenger aircraft "747-xxxSF" special freighters.
Often these "SF" were originally equipped with the SCD Side Cargo Door.
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Same thing happened to to the 400s...
There are differences with air conditioning and fire protection.
Some "conversions" are not entirely similar to "original" freighters.
All depends who made the conversion, and what the customer requested.
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Have a look at number of packs, lower lobe fire protection, and other items.
As usual, if you study any 747, be specific as to "which one" you study.
Besides that, there might be weight limitations differences too.
Differences are just not the nose cargo door.
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Happy contrails