Global liquidity pools are when liquidity pools are shared between all of the different relayers and exchanges using the protocol. Exchanges are incentivized to host orders from other relays and exchanges and mirror order books to maximize the volume on the relayer exchange. bZx enables global liquidity pools.
bZx is creating a bridge between the liquidity pools of the centralized and decentralized exchange ecosystems. This is Universal Liquidity, which goes one step beyond global liquidity. Universal Liquidity bridges together the liquidity of all exchanges and relays.