Can anyone help explain why LlamaIndex is better for indexing and retrieval compared to the LangChain framework? What makes it different from LangChain? If someone can answer this properly, there's a reward, this question asked by me in interview .

have a question for all of you. Feel free to reply, and if you can respond quickly, that would be great. When we use a vector store index in the backend, what is used to create the embeddings? Also, if we don't mention our API key, will it create embeddings, or where do we specify the API key in the vector store index? Can someone clarify how this works?