1. 1. Customizability: Mezzanine CMS offers a high level of customizability, allowing developers to tailor the platform to meet their specific requirements. It provides an intuitive drag-and-drop interface for building websites, making it easy to rearrange content blocks and create unique layouts. On the other hand, Wagtail follows a more opinionated approach, offering a powerful set of out-of-the-box features that are less customizable. While it provides a user-friendly admin interface, its customization options may be more limited compared to Mezzanine.
2. 2. Codebase and Framework: Mezzanine CMS is built on Django, a widely-used Python web development framework. This allows developers familiar with Django to leverage their existing skills and libraries while working with Mezzanine. Wagtail, on the other hand, is built on top of Django as well, but it takes a more modular approach and introduces its own set of APIs and conventions. This difference in codebase and framework can influence the learning curve, development process, and compatibility with existing Django projects.
3. 3. Content Editor Experience: Mezzanine CMS offers a straightforward content editor experience, with a WYSIWYG editor and basic content formatting options. While it provides a simple and user-friendly interface, it may lack some advanced features for content creation. On the contrary, Wagtail places a strong emphasis on content authoring, providing an exceptional editing experience. It includes advanced features such as in-line editing, draft preview, and reusable content blocks, enhancing the content editor's productivity and flexibility.
4. 4. Documentation and Community Support: Mezzanine CMS has a comprehensive and extensive documentation that covers various aspects of development and customization. It also has an active community that provides support and regularly releases updates and bug fixes. Alternatively, Wagtail also has thorough documentation, including a detailed developer's guide and API references. It has a growing community and is backed by Torchbox, a digital agency that actively maintains and contributes to the project. However, the size and maturity of the community may differ, potentially affecting the availability of third-party plugins and community resources.
5. 5. Developer-Friendly Features: Mezzanine CMS offers a range of developer-friendly features, such as built-in SEO tools, code-level customization options, and a modular architecture. It also integrates well with popular third-party libraries and has a plugin system for extending functionality. On the other hand, Wagtail provides a developer-centric approach with features like a flexible content type system, powerful APIs, automatic image optimization, and an easy-to-use template language. These features aim to enhance the developer experience and simplify complex tasks.
6. 6. Project Complexity and Scale: Mezzanine CMS is suitable for small to medium-sized projects, offering a balance between simplicity and functionality. It provides a set of core features that cover typical website needs. In contrast, Wagtail is designed for larger and more complex projects, providing advanced features like multisite support, internationalization, and content import/export capabilities. It can handle enterprise-level websites and has the scalability to accommodate high traffic and extensive content requirements.

In Summary, Mezzanine CMS and Wagtail have key differences in terms of customizability, codebase and framework, content editor experience, documentation and community support, developer-friendly features, and project complexity and scale.