When would you use those, and what's the difference between them?

Partitioning is used when you want to prune entire directories based on query predicates, which is most effective for columns that are frequently used in WHERE clauses and have a manageable number of distinct values. It reduces the amount of data read by skipping irrelevant partitions. File optimization, on the other hand, focuses on the size and layout of the files within each partition. By compacting small files and applying Z‑order clustering, you reduce the number of files that need to be scanned and improve locality of reference for correlated columns. I would use partitioning first to eliminate large swaths of data, and then apply file optimization to fine‑tune performance within the remaining partitions. For example, a sales table might be partitioned by date, and then optimized by Z‑ordering on product_id to speed up queries that filter on both date and product.