The delta sharing protocol is a mechanism to share live data in your Delta Lake without copying it to another system.
Currently it supports delta as the source format. For more details on the advantages of using delta as a table format for data lakes - see here
Unity catalog goes beyond managing tables to govern other types of data assets, such as ML models and files. It brings fine-grained centralized governance to all data assets across clouds through the open standard ANSI SQL Data Control Language (DCL). More details could be found here