Earth Book And Empire II

Poul Anderson's The Earth Book Of Stormgate follows:

Trader To The Stars, three stories about Nicholas van Rijn;

The Trouble Twisters, three stories about van Rijn's protege, David Falkayn, the third story cameoing van Rijn and introducing the trader team led by Falkayn;

Satan's World and Mirkheim, two novels featuring van Rijn, Falkayn and the trader team;
 
The People Of The Wind, a novel about the human-Ythrian colony on Avalon founded by Falkayn.

Also relevant are six earlier short stories covering:

first contact with Ythri;
joint exploration of Avalon;
separate colonization of Avalonian islands;
joint colonization of an Avalonian continent;
two incidents occurring elsewhere between the fourth Ythrian short story and The People Of The Wind.

Against this massive backdrop, the Earth Book collects:

the four Ythrian short stories;
two van Rijn short stories;
one van Rijn novel;
one Falkayn/trader team short story;
one van Rijn/Falkayn/trader team short story;
three other stories about the Polesotechnic League in which both van Rijn and Falkayn are Master Merchants -

- and adds new introductions to all twelve works fictitiously written by an Avalonian Ythrian.

Rise Of The Terran Empire collects:

Mirkheim;
the two short stories about the colonization of Avalon;
the two intermediate short stories;
The People Of The Wind.

Thus, these two omnibus collections overlap by two short stories. Like the two earlier volumes of The Technic Civilization Saga, Rise... preserves the Earth Book introductions where they exist, in this case for the two Avalon short stories.