What is the difference between QuestionAnswerAdvisor and RetrievalAugmentationAdvisor?

QuestionAnswerAdvisor is simple one-shot RAG — search the vector store, append context to the prompt. RetrievalAugmentationAdvisor is a modular pipeline supporting query transformers (rewrite/expand), multiple document retrievers, and document post-processors (re-ranking) — the production-grade, multi-step option.