The Cosmos network consists of many independent, parallel blockchains, called zones, each powered by classical Byzantine fault-tolerant (BFT) consensus protocols like Tendermint (already used by platforms like ErisDB). Some zones act as hubs with respect to other zones, allowing many zones to interoperate through a shared hub. The architecture is a more general application of the Bitcoin sidechains concept, using classic BFT and Proof-of-Stake algorithms, instead of Proof-of-Work.
Cosmos can interoperate with multiple other applications and cryptocurrencies, something other blockchains can't do well. By creating a new zone, you can plug any blockchain system into the Cosmos hub and pass tokens back and forth between those zones, without the need for an intermediary.