What is InstructGPT and Key Differences from ChatGPT

InstructGPT is an advanced iteration of OpenAI’s GPT-3 model, expertly fine-tuned to better understand and execute user commands while producing results that are more ethical, accurate, and in harmony with human intent. This advance marks a significant step in the evolution of AI models, guiding them towards more responsive and ethical interactions. InstructGPT is based on the research paper titled “Training Language Models to Follow Instructions” and its official OpenAI page is here.

Although both InstructGPT and ChatGPT are developed by OpenAI and these two models are based on GPT (Generative Pre-trained Transformer) architecture they are different in methodologies, goals and learning approaches.

Conceptual framework

ChatGPT: Originally designed as a conversational agent, ChatGPT excels at generating human text responses. It is fine-tuned to a combination of supervised and reinforcement learning techniques with an emphasis on conversational tasks.

InstructGPT: Although based on the GPT architecture, InstructGPT is specifically fine-tuned to follow instructions more efficiently. It marks a shift toward aligning model responses with user intent, emphasizing the accuracy and relevance of its results.

Teaching methodology

ChatGPT: Uses a combination of reinforcement learning from human feedback (RLHF), supervised fine-tuning, and a continuous learning process that includes user interaction and subsequent updates.

InstructGPT: Includes a new tutorial mode that includes collecting written demos and preferences. It uses supervised fine-tuning (SFT) followed by further refinement using reinforcement learning from human feedback (RLHF), emphasizing alignment with human instructions and intentions.

Functional goals

ChatGPT: Aims to generate coherent, contextually relevant and engaging dialogue, addressing a wide range of conversational topics while maintaining a natural flow of interaction.

InstructGPT: Focuses on the accurate interpretation and execution of various instructions, striving to produce results that are not only contextually appropriate, but also adhere precisely to the specific guidelines provided by the user.

Performance and capabilities

ChatGPT: Demonstrates robust conversational capabilities capable of supporting long and complex dialogues across domains, but may not always conform to specific user instructions.

InstructGPT: Shows significant improvement in following specific instructions, providing outputs that are more consistent with user requests, even for tasks that are less conversational and more direct in nature.

Assessment and metrics

ChatGPT: Evaluated primarily on its ability to support engaging and contextually relevant conversations, with metrics often centered around dialogue coherence, fluency, and user engagement.

InstructGPT: Evaluated on the user’s adherence to and execution of instructions, with a strong emphasis on the accuracy, relevance, and usefulness of his responses in relation to the specific tasks given.


In summary, while both models share a common foundation in the GPT architecture, InstructGPT represents a purposeful evolution toward better understanding and execution of user instructions, distinguishing it from the more conversational ChatGPT. This change underscores OpenAI’s commitment to improving the practical utility and user experience of language models in real-world applications.

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