How are network sites related?

I've been reading the threads about the horrible experiences with OddsMaker. I went to poker scout to check out its network affiliations:
Merge Gaming Network live traffic report | PokerScout

There I find the 18 sites of the MERGE network listed, and see that the site I play most on, Carbon Poker, is a MERGE site. Some of the others are PokerNordica, Reefer and BetOnUSA.

My question is: what does it mean for sites to share a network? Are they essentially the same business with the same people running them and the same policies? Or are they independent sites sharing resources and perhaps facilities?

I believe Carbon to be a reputable site. CardsChat has tournies on there. What does it mean that Carbon shares a network with the notorious OddsMaker?
Gary

BUMP

im not sure here so really dont know but i think its all kinda the same software becuz all the tbles and lobbys and backgrounds at those sites all look the same i dont think its the same ppl just think its the same type of graphics engine etc. but again i really have no idea but i have noticed that too