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In-context learning vs RAG in LLMs: A Comprehensive Analysis

RAG and ICL have emerged as techniques to enhance the capabilities of LLMs

In the rapidly evolving field of natural language processing (NLP), two prominent techniques have gained significant attention: Retrieval Augmented Generation (RAG) and In-context Learning (ICL). Both methods aim to enhance the capabilities of language models, yet they differ fundamentally in their approach and application. This article explores these differences, shedding light on the strengths, weaknesses, and use cases of each method.

Table of contents

  1. Retrieval Augmented Generation (RAG) in LLMs
  2. Overview of In-context Learning
  3. In-context Learning vs RAG
  4. Real-world use case

Let’s start with an understanding of RAG working in LLMs.

Retrieval Augmented Generation (RAG) in LLMs

RAG is a hybrid approach that combines the strengths of retrieval-based methods with generative models. It consists of two primary components:

  • Document Retriever: This component searches a large corpus to retrieve relevant documents based on a query.
  • Text Generator: Using the retrieved documents, this component generates a response that integrates the information found.

RAG is particularly effective for tasks that require specific information from a large corpus, such as question answering, information extraction, and summarization. By leveraging external data sources, RAG can provide detailed and contextually rich responses. RAG has several advantages:

  1. It allows LLMs to access up-to-date information.
  2. It can provide more accurate and specific responses, especially for factual queries.
  3. It helps mitigate hallucinations or incorrect information generation by grounding the LLM’s responses in external data.

Overview of In-context Learning

In-context learning, also known as few-shot learning or prompt engineering, is a technique where an LLM is given examples or instructions within the input prompt to guide its response. This method leverages the model’s ability to understand and adapt to patterns presented in the immediate context of the query.

Key aspects of in-context learning include:

  • Providing examples: The prompt includes one or more examples of the desired output format or content.
  • Task description: Clear instructions about what the model should do are included in the prompt.
  • Zero-shot, one-shot, or few-shot learning: Depending on the number of examples provided (none, one, or a few).

In-context learning allows LLMs to perform tasks without fine-tuning or additional training, making it a flexible and efficient approach for various applications.

In-context Learning vs RAG

Feature Retrieval Augmented Generation (RAG)In-context Learning (ICL)
DefinitionCombines retrieval of relevant documents with text generation based on those documents.Uses prompted examples to generate appropriate responses.
Primary ComponentsDocument Retriever and Text GeneratorPre-trained Language Model and Contextual Prompts
Data DependencyRelies on external data sources for document retrieval.Depends on the examples provided in the prompt.
Context UtilizationUses retrieved documents to provide additional context for generation.Use examples in the prompt to understand the task context.
FlexibilityCan handle a wide range of queries by retrieving different documents.Limited to the patterns learned from the provided examples.
StrengthsEffective for tasks requiring specific information from a large corpus.Simple and efficient for tasks where examples are clear and context is well-defined.
WeaknessesRequires efficient retrieval mechanisms and relevant documents.Performance depends heavily on the quality and relevance of prompt examples.
Use CasesQuestion answering, information extraction, summarization.Few-shot learning, tasks with limited training data.
ComplexityMore complex due to the need for integrating retrieval and generation.Simpler as it relies solely on the language model and prompt design.
ExamplesOpenAI’s GPT-3 combined with a retrieval system for answering queries.GPT-3 generates text based on a few provided examples in the prompt.

Real-world use case

Consider a real-world example illustrating the difference between RAG and in-context learning. In this use case, we would take a customer service chatbot for a large electronics retailer as a scenario.

Scenario: A customer asks about the latest features of a newly released smartphone model.

In-context Learning Approach

Prompt to the LLM : 

You are a customer service representative for ElectroTech, a major electronics retailer.
When customers ask about product features, provide a brief, friendly response.
Here’s an example:

Customer: What are the main features of the LapPro X1 laptop?
Representative: The LapPro X1 features a 15-inch 4K display, 16GB RAM, 1TB SSD, and the latest 12th Gen Intel i7 processor. It’s perfect for both work and entertainment!

Now, please respond to this customer query:
Customer: What are the new features in the GalaxyPhone 15?

LLM Response: 

Representative: The GalaxyPhone 15 comes with an impressive 6.7-inch AMOLED display, a powerful triple-lens camera system, 5G capability, and an all-day battery life. It’s a great choice for smartphone enthusiasts who want top-notch performance and photography features!

In this case, the LLM uses the example provided in the prompt to understand the format and style of the response. However, the specific features mentioned for the GalaxyPhone 15 may not be accurate or up-to-date, as the LLM is relying on its pre-trained knowledge, which may be outdated.

RAG Approach

In a RAG system, the process would look like this:

  1. The customer’s query is received: “What are the new features in the GalaxyPhone 15?”
  2. The system searches its up-to-date product database for information about the GalaxyPhone 15.
  3. Relevant information is retrieved and provided to the LLM along with the query.
  4. The LLM generates a response based on this retrieved information.

LLM Response (with RAG):

Representative: I’m excited to tell you about the new GalaxyPhone 15! It features a groundbreaking 200MP main camera, a 6.8-inch Dynamic AMOLED 2X display with adaptive refresh rate up to 120Hz, the latest Snapdragon 8 Gen 2 processor, and a 5000mAh battery with 45W fast charging. It also introduces satellite connectivity for emergencies and enhanced AI capabilities for improved photo editing and voice recognition. Is there any specific feature you’d like more details on?

Key Differences:

  • Accuracy: The RAG approach provides more accurate and current information about the specific product, as it pulls data from an up-to-date database. The in-context learning approach, while capturing the right tone and format, may provide outdated or incorrect specifics.
  • Specificity: RAG allows for more detailed and product-specific information, while in-context learning provides a more general response based on the model’s pre-existing knowledge.
  • Adaptability: In-context learning can quickly adapt to different types of products or queries based on the provided example, even if it doesn’t have specific information. RAG is more rigid but excels when accurate, up-to-date information is crucial.
  • Maintenance: The in-context learning approach requires updating the prompt examples to keep information current, while the RAG approach requires maintaining an up-to-date product database.


As we move forward, the synergy between RAG and in-context learning will undoubtedly play a pivotal role in shaping the future of AI-powered solutions across various industries, from customer service and content creation to scientific research and beyond.


  1. How does in-context learning works
  2. Enhancing Retrieval-Augmented Generation in NLP

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Sourabh Mehta

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