1. Target Audience: Felgo Game Engine is primarily focused on indie game developers and enthusiasts who want to create 2D and 3D games with ease, while three.js is more suitable for developers looking to create complex 3D visualizations and experiences.
2. Ease of Use: Felgo Game Engine provides a more user-friendly and visually intuitive interface for game development, offering drag-and-drop components and a visual scene editor, whereas three.js requires a stronger understanding of JavaScript and WebGL for implementation.
3. Community Support: Felgo Game Engine has a smaller but more specialized community that is dedicated to game development, offering extensive documentation, tutorials, and dedicated support, while three.js has a larger and more diverse community with a broader range of applications beyond gaming.
4. Compatibility and Integration: Felgo Game Engine provides seamless integration with popular game development platforms like Qt/QML and Felgo Cloud services for online features, whereas three.js offers greater compatibility with other libraries and frameworks, allowing for more customization and flexibility in development.
5. Performance Optimization: Felgo Game Engine streamlines optimization processes for mobile platforms, offering features like automatic multi-resolution support and texture compression, while three.js requires more manual optimization to achieve optimal performance on different devices.
6. Pricing Model: Felgo Game Engine follows a subscription-based pricing model with different tiers based on the needs of individual developers, while three.js is an open-source library free for commercial use without any licensing fees.

In Summary, Felgo Game Engine is tailored towards indie game developers with user-friendly interfaces and optimization features, while three.js is more suited for complex 3D visualizations and applications with a strong emphasis on customization and performance.