Security
User must have SELECT permission on an external table to read the data. External tables access underlying Azure storage using the database scoped credential defined in data source.
Note: A database scoped credential is a record that contains the authentication information that is required to connect to a resource outside SQL Server. Most credentials include a Windows user and password.
Reference:
https://docs.microsoft.com/en-us/azure/synapse-analytics/sql/develop-tables-external-tables
https://docs.microsoft.com/en-us/sql/t-sql/statements/create-database-scoped-credential-transact-sql

The Databricks ABS-AQS connector uses Azure Queue Storage (AQS) to provide an optimized file source that lets you find new files written to an Azure Blob storage (ABS) container without repeatedly listing all of the files.
This provides two major advantages:
Lower latency: no need to list nested directory structures on ABS, which is slow and resource intensive.
Lower costs: no more costly LIST API requests made to ABS.
Reference:
https://docs.microsoft.com/en-us/azure/databricks/spark/latest/structured-streaming/aqs

Linked services are much like connection strings, which define the connection information needed for Data Factory to connect to external resources.
Reference:
https://docs.microsoft.com/en-us/azure/data-factory/enable-customer-managed-key
https://docs.microsoft.com/en-us/azure/data-factory/concepts-linked-services
https://docs.microsoft.com/en-us/azure/data-factory/create-self-hosted-integration-runtime

According to Microsoft Purview Data Catalog lineage user guide1, data lineage in Microsoft Purview is a core platform capability that populates the Microsoft Purview Data Map with data movement and transformations across systems2. Lineage is captured as it flows in the enterprise and stitched without gaps irrespective of its source2.