Okies series and the CoDominium future history is a Prime Directive against interference in lower level societies although the only way to ensure no interference would be to prevent any interaction. By contrast, the Allied Planets of Poul Anderson's Technic History assess isolated planets in order to determine whether the attempt to recivilize them is worth the effort.
In King David's Spaceship, Jerry Pournelle shows the high tech Second Empire interacting with two isolated planets of different levels. The main difference seems to be that men on Prince Samual's World fight with guns whereas the inhabitants of Makassar use swords. The planets differ in other physical and sociological details and are realized in commendable detail.
I get the impression that the CoDominium History primarily comprises:
the Falkenberg series (4 vols);
War World (5);
the Second Empire (3) -
- which in turn correspond to three historical periods:
the Old Empire;
the New Empire and First Contact.
It is like a shorter alternative to the Technic History.