There are a few, but I'll stick to the 2 main differences.

Blocknet is a trustless interoperability protocol that enables the transfer of data and value across different blockchains. The Blocknet DEX is built on this protocol. Anyone else can build a DEX or other services using this protocol as well and liquidity is shared among all the services.

Blocknet DEX is also trustless while cryptobridge is not. A few weeks ago cryptobridge users were having issues with deposits and withdrawals where the team had to help the users out. This is one of a few key indicators for whether an exchange is truly decentralized or of it is a hybrid exchange. With a trustless DEX like Blocknet's,  every trade is done from the users own wallet. The only support the Blocknet team would be able to give is usability related since everything else is trustless.