Dedicated SQL Pool
Designed for Kimball style star/snowflake schema data warehouses.
Billed for storage and compute. Can be paused.
Contains tables (internal, external, temp), views, procedures - it is a database.
Internal tables are columnstore.
Does not support OPENROWSET, external tables must be explicity created.
Query language is TSQL.
Serverless SQL Pool
Designed for data processing, not data storage.
Billed per-use for compute only. Has cost budgets and limits.
Does not contain internal tables, just external and temporary.
Query language is TSQL.