Google has built a class of AI tools designed to solve a common problem: how do you absorb complex information faster? But in doing so, it's left a lot of users confused about the differences between these tools.
At first glance, NotebookLM, Audio Overviews and Illuminate all seem very similar. They all promise to make dense material easier to digest. But they are designed for very different workflows. One is a smart research notebook. One turns your documents into a podcast-style explainer. And one creates listening-first audio summaries for academic papers.
The best tool depends on how deep you want to go and whether you’re reading, listening or researching on a deadline.
NotebookLM
NotebookLM is Google’s AI-powered research assistant built around your own sources. You upload or link documents, then ask questions, generate summaries or create structured outputs — all grounded in your materials. The most recent update just allowed for web searching, too. So, now you can add online sources to your research. You can add PDFs, Google Docs and Slides, web pages, YouTube videos (via transcripts), notes and reference materials to NotebookLM.
From there, NotebookLM goes beyond basic Q&A. It’s designed for deeper synthesis, including study guides, briefs, outlines, key takeaways across multiple sources, quote extraction with inline citations and clear explanations for complex topics.
Use NotebookLM if you want:
- An interactive, citation-driven research notebook
- Accurate, source-grounded responses
- Cross-document synthesis and follow-up questions
- Study guides, outlines and explainers
- Traceability, structure and smart summaries
Audio Overviews
Here is where I got mixed up the first time I heard about Audio Overviews. Originally a feature inside NotebookLM,, Audio Overviews are now a tool on their own. You can use the feature within NotebookLM to turn your sources into a podcast-style explanation — usually voiced as a conversation between two AI narrators or as a completely separate tool outside of NotebookLM.
Because I'm in NotebookLM all the time anyway, I personally have found Audio Overviews easier to use within the platform. What I like about Audio Overviews is that the tool isn't a typical text-to-speech tool, instead Audio Overviews reframe your documents as an engaging audio discussion, highlighting what the material is about. It's great because you can listen while driving, walking or multitasking and still return to NotebookLM to follow up or explore quotes with citations.
Audio Overviews hint at where AI assistants are heading with screen-optional learning, multimodal comprehension and research you can consume on the go. For anyone who’s too busy to sit down and read, this makes dense content much more accessible.
Use Audio Overviews if you want:
- A podcast-style summary of your NotebookLM sources
- A way to learn while multitasking
- Audio you can play alongside your notebook
Illuminate
Google Labs – Illuminate is a standalone Google tool designed to turn academic and technical research into audio explainers. If this is leaving you scratching your head like, "Wait, isn't that NotebookLM?" trust me, there is a difference. Where NotebookLM is a workspace, Illuminate feels more like a pre-recorded podcast episode. It's essentially a polished audio summary you can listen to without needing to ask follow-up questions.
To use Illuminate simply upload or link to a research paper. From there, Illuminate generates a listening-first audio summary. The result feels like a guided explainer so it's perfect for those times when you think, “I want to understand this paper, but I don’t want to read it.”
I use it for AI white papers all the time. I don't need a podcast like with Audio Overviews or NotebookLM, I just need to hear the information because I don't have time to read it. It's a great tool for students, researchers, lifelong learners or anyone tackling complex research or white papers professionally.
Use Illuminate if you want:
- A fast, passive explainer for complex research
- High-level framing with no interaction needed
- A “make this understandable” button for dense studies
Bottom line
TL:DR: Audio Overviews explain your NotebookLM sources; Illuminate creates standalone summaries for academic papers.
Despite their differences, all three tools share some common DNA. They are all powered by Gemini 3.0 and are free to use. Each one of these tools treat audio as a core feature and prioritize understanding over surface-level summaries.
But if you ask me, the most effective workflow is combining the tools. For example, start with Illuminate to get the gist of a new research paper, then follow with NotebookLM to dig deeper, ask questions and pull quotes. Finally, listen by while outlining, writing or communiting to class.
This combo is especially powerful for journalists, students or researchers working on deadlines. If you’ve ever said, “I don’t have time to get through all of this,” these AI tools were built for you.
More from Tom's Guide
- The AI trick everyone overlooks — and it makes every prompt more powerful
- I tested ChatGPT-5.2 vs Gemini 3.0 with 7 real-world prompts — here's the winner
- The ‘no prompt’ rule makes ChatGPT give expert-level writing advice — here’s how it works
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