What’s the difference between RAG and Fine-Tuning?

Retrieval-Augmented Generation (RAG) and fine-tuning both aim to improve the performance and applicability of language models, but they do so in fundamentally different ways.

What’s the difference between RAG and Fine-Tuning?
Jay Marciano
Jan 29, 2024

Two methods for enhancing LLM functionality

As Lengoo forges ahead in leveraging the strengths and mitigating the weaknesses of large language models, we continue to explore methods for improving their effectiveness for specific use cases. Two key methodologies that have emerged are Retrieval-Augmented Generation (RAG) and fine-tuning. While both approaches aim to improve the performance and applicability of language models, they do so in fundamentally different ways. In this blog post, we will delve into the differences between RAG and fine-tuning, exploring their unique characteristics, applications, and impacts on the field of AI.

Let’s call them “foundation models” for a second

While the moniker “large language model” is more commonly used these days, the name “foundation model” is in some ways a more precise and inclusive term for these drivers of the current surge in AI. “Foundation model” doesn’t focus solely on language ‒ and therefore logically includes multimodal models that generate not only language but also images, code, and other content types ‒ and emphasizes that these massive general models can serve as the basis or foundation of more efficient models that are specialized on particular use cases.

RAG and fine-tuning are two methods for enhancing the output of a foundation model, and they are not mutually exclusive, meaning that they can, in fact, be used together. 

Retrieval-Augmented Generation (RAG)

RAG combines the power of a pre-trained language model with external and potentially dynamic data sources that were not part of the model’s training and a knowledge retrieval mechanism.

RAG operates by first using a query mechanism to retrieve relevant information from one or more external datasets or knowledge bases. This retrieved information and the original prompt are then fed into a generative AI model, which integrates this external data into the generation of its response. This process allows the model to produce answers that are not just based on its pre-trained knowledge but also on potentially more recent and relevant external data.

RAG is particularly useful in scenarios where up-to-date information is crucial, such as news summarization, real-time question answering, and research assistance. It’s also beneficial in situations where the language model needs to reference specific data points or statistics that it wouldn't have been exposed to during its initial training.

Fine-Tuning of Large Language Models

Fine-tuning, on the other hand, is a process of adapting a pre-trained foundation model to a specific task or dataset. This approach involves continuing the training of a model on a smaller, task-specific dataset, allowing the model to adjust its parameters to better suit the requirements of the task.

In fine-tuning, the pre-trained model is essentially 'tweaked' using a smaller, specialized dataset. This process helps the model to understand the nuances and specificities of the task at hand. The fine-tuning phase is usually much shorter than the initial training phase and requires less computational resources.

Fine-tuning can be used to refine a foundation model for any task that can be adequately represented in a specialized data set, one that juxtaposes starting points and acceptable end points for such a task.  such as sentiment analysis, legal document analysis, and medical report generation, where the language model needs to be particularly attuned to the specific jargon, style, and requirements of the field.

Comparing RAG and Fine-Tuning

While both RAG and fine-tuning enhance the capabilities of foundation models, they do so in different ways and for different purposes.

  • Knowledge integration vs. task specialization: RAG focuses on integrating external knowledge into the generation process, making the model more versatile and up to date, while fine-tuning specializes the model for a specific task, making it more accurate and efficient in that context.
  • Dynamic vs. static learning: RAG allows the model to access and use external information dynamically, which means it can stay current with the latest data. Fine-tuning is a more static approach, as the model is only as up to date as the data in its most recent training session.
  • Generalization vs. customization: Used alone, RAG maintains the general-purpose nature of the foundation model while augmenting it with external data. Fine-tuning customizes the model for a specific task, potentially reducing its effectiveness in general language tasks.
  • Resource Intensity: RAG requires a mechanism to retrieve and integrate external data, which can be resource intensive. Fine-tuning, while also resource-intensive during the training phase, does not usually require additional resources during deployment.

Summing it up

Retrieval-augmented generation and fine-tuning are different but potentially complementary approaches to enhancing the functionality of a foundation model. RAG extends the model's capabilities by incorporating real-time external data, making it more versatile and informed than its original training data would allow. Fine-tuning, in contrast, adapts the model to perform exceptionally well in a specific context. Both methodologies are crucial in the ongoing development of AI and machine learning, offering unique solutions to the ever-evolving challenges of language understanding and generation.