Why is Azure SQL DB used space larger than physical server storage used space?
It’s difficult to answer without knowledge about the specifics. However, in Azure SQL Database Accelerated Database Recovery (ADR) and Read-Committed Snapshot are both on by default, which is on the case on-prem. This means that the Persistent Version Store might take up space in Azure.
But as I understand, the databases has different sets of data, so maybe you are simply mistaken about what you think should be the same size. Attached is a file with a couple of queries to give you the size of tables in the database. (The queries handle LOB data a little differently.)
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