While it mainly goes undisputed that John Marston is Jack Marston ... between the two is that John is an outlaw and a gunslinger, whereas Jack is more sheltered and scared.
The ride isn't over in Red Dead Redemption 2 just because the credits have rolled, and there are still plenty of things to do ...
Jack Marston remains kind ... But while many no-good outlaws and opportunistic dictators pride themselves on trampling over the less fortunate to ensure their survival, wealth, and prosperity ...