1. Customizability: Buildroot offers a higher level of customizability compared to Ubuntu. With Buildroot, users can tailor their embedded Linux systems to specific requirements by selecting only the necessary components and optimizing them for their target hardware. On the other hand, Ubuntu provides a pre-configured set of packages and applications, which may not be as flexible or customizable for specific use cases.

2. Package Management: Ubuntu utilizes a package management system called Advanced Packaging Tool (APT), which provides an extensive repository of pre-compiled software packages that can be easily installed, updated, and removed. In contrast, Buildroot uses a different approach where packages are built from source during the build process. This allows users to have more control over the versions and configurations of the software components, but it requires additional effort for maintaining and updating packages.

3. System Size: Buildroot focuses on minimizing the system size to fit into resource-constrained embedded devices. It allows users to create a minimalistic system containing only the necessary components, resulting in a smaller footprint. On the other hand, Ubuntu is a full-fledged operating system with a comprehensive set of applications and features, which translates to a larger system size compared to Buildroot.

4. Ease of Use: Ubuntu is renowned for its user-friendly interface and ease of use, making it suitable for general-purpose computing. It provides a desktop environment with intuitive graphical interfaces, a vast array of applications, and comprehensive documentation for beginners. Buildroot, on the other hand, requires advanced knowledge of Linux and embedded systems as it primarily targets developers and engineers who have expertise in building custom Linux systems from scratch.

5. Community Support: Ubuntu has a large and active community of users and developers, which results in extensive community support. Users can readily find help, tutorials, and online forums for troubleshooting and learning. Buildroot also has a community, but due to its niche use case and advanced nature, the community may be smaller and the available resources may not be as abundant as those for Ubuntu.

6. Target Audience: Buildroot and Ubuntu target different audiences. Buildroot is intended for embedded systems developers who need to create customized and optimized Linux systems for resource-constrained devices. In contrast, Ubuntu targets a broader audience, including casual users, developers, and enterprises, aiming to provide a user-friendly and versatile operating system for general-purpose computing.

In summary, Buildroot and Ubuntu differ in terms of customizability, package management, system size, ease of use, community support, and target audience. Buildroot offers high customizability, requires manual package management, focuses on system size optimization, requires advanced knowledge, has a smaller community, and targets embedded systems developers. On the other hand, Ubuntu provides a pre-configured system, utilizes a package management tool, has a larger system size, offers user-friendly interfaces, has extensive community support, and targets a broader audience.