Evaluate the differences between create_stuff_documents_chain and create_retrieval_chain

[bossjones]

Built-in chains

If preferred, LangChain includes convenience functions that implement the above LCEL. We compose two functions:

• create_stuff_documents_chain specifies how retrieved context is fed into a prompt and LLM. In this case, we will "stuff" the contents into the prompt -- i.e., we will include all retrieved context without any summarization or other processing. It largely implements our above rag_chain, with input keys context and input-- it generates an answer using retrieved context and query.
• create_retrieval_chain adds the retrieval step and propagates the retrieved context through the chain, providing it alongside the final answer. It has input key input, and includes input, context, and answer in its output.