While I know what your saying, and agree they may have been intended to be the same thing, as I said earlier in the thread in context the two are very different things. General Order Seven might specifically seem to apply to Talos IV alone, or at least that's how it's presented to us: a very specific scenario involved in (wilfully) breaking the most highest of curfews placed in order to protect outsiders from the dangers posed by the powerful (and antagonistic) Talosians. General Order 4 is presented as being some kind of on-board-ship law, something that could be pulled out and used in some mutinous circumstance or other. It's not necessarily used often, it might not be used at all. But that it exists is troubling, and says that in Kirk's time at least there's still a certain brutality to the human condition.
There is a contradiction between "The Menagerie", which says blatantly that GO7 was the only death penalty still left on the books, and "Turnabout Intruder", which implies that GO4 is also a death penalty. But we must assume that in-universe each are separate and both carry the same sentence.
That's rather speciest of you, Humans are not the only Federation members, are they?
To any number of the other Federation members, no death penalty may be seen as an absurdity, so the compromise was to have just one on the books. Unless Starfleet is a Homo Sapiens club only.