Zilliqa utilizes pBFT protocol to ensure security of the network. pBFT assumes that portion of the nodes within the network is hostile. Based on that, each node has to independently verify all transactions in the network and share the results with other nodes. Consensus is reached by the majority of the nodes.
Zilliqa offers transaction finality unlike its competitors which means that there is no need to wait for confirmations. This also eliminates double spending risk and provides additional speed improvement.