1. Styling Approach: Emotion is a CSS-in-JS library that generates real CSS classes for styling components, while Glamorous is a higher-level abstraction on top of Emotion that simplifies styling using JavaScript objects directly.
2. API Usage: Emotion provides a more comprehensive API with functionalities like global styles, composition, and theming, whereas Glamorous streamlines the styling process by offering a concise API that focuses on simplicity and readability.
3. Component Styling: Emotion supports component-based styling, enabling the creation of styled components through JavaScript, while Glamorous promotes a more concise approach by allowing inline styling without the need for defining separate styled components.
4. Theming Support: Emotion offers robust theming capabilities for creating consistent and reusable design systems, whereas Glamorous provides limited theming support, focusing more on component styling rather than theming.
5. Community Support: Emotion has a larger and more active community, contributing to its extensive documentation, support forums, and a wide range of integrations, while Glamorous, although backed by the same community, has a smaller user base and fewer resources available.
6. Performance Optimization: Emotion is known for its optimized performance through features like server-side rendering and dynamic styling, while Glamorous, being a higher-level abstraction, may introduce overhead in certain scenarios that require fine-tuning for performance.

In Summary, Emotion and Glamorous libraries differ in their styling approach, API usage, component styling, theming support, community engagement, and performance optimization capabilities.