Warehouse vs Lake vs Lakehouse

A warehouse enforces schema-on-write with tight governance and fast SQL; a data lake stores raw files cheaply with schema-on-read and no transactions; a lakehouse puts an open table format (Iceberg or Delta) on object storage to give ACID, time travel, and schema evolution at lake cost. The choice is about cost, governance, and workload, not vendor preference. Applied-AI interviews probe it because candidates conflate the three and cannot say which fits BI versus ML versus streaming ingest.