Selecting the Best Search Option for Knowledge Copilot: Azure AI Search vs. Copilot Semantic Index

Choosing the Right Search Approach for Knowledge Copilot Solutions

Since the launch of Microsoft Copilot, many organizations have wanted to take advantage of its powerful capabilities. But there’s been a catch—every user needed a full Microsoft 365 Copilot license, making it a bit expensive to explore. However, thanks to an update on January 14th, 2025, that’s no longer the case! Now, businesses can access Copilot’s advanced features, including the Copilot Semantic Index, without the need for every user to have a full license. This opens up a world of opportunities to enhance knowledge management and improve user experience without breaking the bank.

Current Copilot licensing is a whole other kettle of fish we'll get into another day.

But let’s take a step back and understand what’s actually driving this change. At the core of Copilot’s magic is its ability to search and analyze data. So, when it comes to choosing the right search solution for your Knowledge Copilot, it’s crucial to understand how the different options work. This is where things like Azure AI Search and Copilot Semantic Index come in—two powerful search tools that can shape how well your Copilot solution performs.

Link: Microsoft Documentation

What is Azure AI Search?

Imagine you’re trying to find a specific book in a massive library. If you only had a basic catalog system (like a keyword search), you might find a book with the right title but the wrong content, or even miss some relevant books altogether. This is how traditional search systems work—based on keywords alone.

Now, think of Azure AI Search as an upgraded, smart librarian who can not only locate books by title but also understand the content of every page and recommend the perfect book based on what you really need—whether it's hidden away in a dusty corner or listed under a different topic. Azure AI Search is designed to handle AI workloads and offers a variety of search techniques, including Semantic, Keyword, and Vector search, so it can return more accurate and context-aware results. It’s like having a search engine that’s constantly learning and improving, offering up exactly what you need, no matter how complicated the request.

What is Copilot Semantic Index?

Now, let’s zoom in on Copilot Semantic Index, which is another powerful tool you’ll want to consider for your Knowledge Copilot setup. If Azure AI Search is the smart librarian, the Semantic Index is more like the system that organizes all the books based on their meaning, not just their titles or keywords. It uses AI to understand the context of content, so when you search for something, it doesn’t just match the words—you get results based on the meaning behind those words.

For example, if you’re looking for documents on “data security,” the Semantic Index understands that documents on “protecting information” or “cybersecurity” are relevant too, even if they don’t have the exact phrase you typed. This deeper understanding improves the quality of search results, making your Knowledge Copilot experience feel much more intuitive and efficient. Before the January 14th update, this advanced feature required a full Microsoft 365 Copilot license for every user. But now, you can access it without that extra cost.

Key Considerations for Selecting a Search Strategy

The AI landscape is evolving rapidly, with Microsoft continually refining its offerings to enhance functionality and performance. One crucial factor in delivering an effective Knowledge Copilot experience is the underlying search technology. We've found that the overall quality and user satisfaction of Copilot solutions are directly tied to the effectiveness of search results.

In our experience, leveraging Azure AI Search has consistently yielded superior outcomes for our clients. This advanced search solution is designed to support AI workloads, offering a range of search techniques including Semantic, Keyword, Vector, and hybrid models. These capabilities enable more precise and relevant search results compared to traditional methods.

Cost vs. Performance: A Comparison

When considering Azure AI Search vs. Copilot Semantic Index, one of the biggest factors to weigh is cost vs. performance.

• Azure AI Search provides powerful performance but comes with a price. Implementing it requires investments in resources like Copilot Studio, Azure Open AI, and Azure AI Search itself. While the upfront costs can be high, the benefits are clear: you get advanced search capabilities and a customizable experience that can scale with your business needs. If you’re aiming for high-quality results and your organization has the resources to invest, Azure AI Search might be the best fit. It was previously the cheaper licensing option ongoing too until the recent January option.
• On the other hand, Copilot Semantic Index offers a more refined search experience and is a more cost-effective option, especially after the recent licensing update. While it doesn’t offer the full range of customization and flexibility that Azure AI Search does, it provides a good balance of performance and cost for many businesses. It’s a great choice if you want more accurate, context-aware results without the hefty investment required by Azure AI Search.

Factors to Consider When Making Your Decision

When deciding between Azure AI Search and Copilot Semantic Index, consider the following factors:

1. Performance Needs: Do you need highly customizable and scalable search capabilities that can grow with your business? If so, Azure AI Search may be the better choice. It’s designed to support complex AI workloads and can handle a variety of search models, making it ideal for larger organizations with diverse needs. On the flip side, if your search requirements are more straightforward, Copilot Semantic Index may provide the level of performance you need with less complexity.
2. Cost: What’s your budget? Azure AI Search can be expensive, especially when factoring in the required Azure resources. If cost is a major consideration, Copilot Semantic Index offers a more affordable alternative, especially since you no longer need full Copilot licenses for every user.
3. Search Quality: Both tools offer high-quality search results, but Copilot Semantic Index shines when it comes to delivering context-aware results. If you're looking for highly relevant information based on meaning rather than just keywords, Copilot Semantic Index may be the right choice. Azure AI Search, while also powerful, provides a broader search experience with more options for customization.
4. Licensing and Accessibility: With the recent update, Copilot Semantic Index is now much more accessible, as it no longer requires a full Microsoft 365 Copilot license for every user. If licensing costs were a barrier for your organization, this update might make it an easier option to implement. Azure AI Search, while highly effective, may still require additional investment in licenses and resources.

Final Thoughts

Choosing the right search strategy for your Knowledge Copilot is a critical decision that will impact the effectiveness and user satisfaction of your solution. Azure AI Search offers powerful, customizable search capabilities for complex needs but comes at a higher cost. Copilot Semantic Index, on the other hand, provides a cost-effective solution with excellent context-aware search, making it a great choice for businesses looking for relevant, high-quality results without the hefty price tag. By weighing performance, cost, and licensing considerations, you can make an informed decision about which search solution is right for your business.

Kim Brian

Modern Applications and Power Platform Solutions Architect at Velrada .

Technical Consultant Helping organizations unlock the full potential of their Microsoft efficiency tools.

Feel free to share your thoughts or connect with me to discuss AI or Microsoft efficiencies.