The Apache Spark Connector for SQL Server and Azure SQL is based on the Spark DataSourceV1 API and SQL Server Bulk API and uses the same interface as the built-in JDBC Spark-SQL connector. This allows you to easily integrate the connector and migrate your existing Spark jobs by simply updating the format parameter!
This appears to be different from the old Spark connector to Azure SQL Database and SQL Server. Also, for anyone potentially confused between it and PolyBase, this is going in the opposite direction: the Spark connector lets you access a SQL Server from an Apache Spark cluster, reading SQL Server’s data and processing it across a number of executor nodes. By contrast, PolyBase lets you read data stored in Spark SQL tables from SQL Server, virtualizing it so that it looks like a regular SQL Server table.