1. Grid System: Bootstrap uses a 12-column grid system while Material Design for Angular and Topcoat utilize different grid structures, with Material Design following Google's guidelines and Topcoat focusing on simplicity and performance.

2. Design Philosophy: Bootstrap follows a more traditional design approach with a focus on consistency and utility, while Material Design for Angular emphasizes meaningful motion, depth, and visual cues to create a more immersive user experience. Topcoat, on the other hand, adopts a minimalist design philosophy with a strong emphasis on performance optimization.

3. Components and Customization: Bootstrap offers a wide range of components out-of-the-box, allowing for easy customization through its extensive documentation and community support. Material Design for Angular provides components that adhere strictly to Google's Material Design guidelines, offering a cohesive visual language across different platforms. Topcoat offers a lightweight set of UI components that are highly customizable, aiming for simplicity and flexibility.

4. Integration with Angular: Material Design for Angular is specifically designed to seamlessly integrate with Angular frameworks, providing developers with pre-built components and services that align with Angular best practices. Bootstrap, although widely used with Angular, may require additional effort for integration due to differences in design principles and component structures. Topcoat also offers integration with Angular, focusing on providing efficient, lightweight components that work well within an Angular environment.

5. Animation and Transitions: Material Design for Angular places a strong emphasis on animations and transitions to enhance user interactions and convey the hierarchy of elements on the screen. Bootstrap also offers animation utilities, but they are not as integral to the design framework as in Material Design. Topcoat, being focused on performance, keeps animations to a minimum to ensure fast loading times and smooth user experience.

6. Theming and Styling: Material Design for Angular and Bootstrap both offer comprehensive theming and styling options, allowing developers to easily customize the look and feel of their applications. Topcoat, while providing some level of theming capabilities, prioritizes a consistent design language and performance optimization over extensive theming options.

In Summary, the key differences between Bootstrap, Material Design for Angular, and Topcoat lie in their grid systems, design philosophies, components and customization options, integration with Angular, approach to animation and transitions, and theming and styling capabilities.