What is the difference between ETL and ELT?
ETL (extract, transform, load) and ELT (extract, load, transform) are both ways to move data from many sources into a warehouse or lake for analytics, but they reverse the middle steps. In ETL, data is cleaned and reshaped on a separate processing layer to match the target schema, then loaded only after it is ready. In ELT, raw data is loaded first into a powerful target system (often a cloud warehouse or lake), and transformations run there later as analytics needs dictate. According to AWS, ETL usually needs more upfront definition of types and structures and is common for legacy loads, while ELT has become the modern default because cloud targets can scale transforms after ingest.
Source: AWS — ETL vs ELT