1. User Interface: Excalidraw has a simple and intuitive user interface that focuses on freehand drawing, while JointJS offers a more structured diagramming approach with a wide range of pre-built shapes and elements to choose from.
2. Collaboration Features: Excalidraw excels in real-time collaboration with multiple users drawing simultaneously and viewing changes instantly, whereas JointJS lacks robust real-time collaboration features.
3. Export Options: Excalidraw allows users to export drawings as PNG, SVG, or JSON files, whereas JointJS focuses more on exporting diagrams as SVG or VML for easy integration into web applications.
4. Customization Abilities: JointJS offers extensive customization options in terms of styling, behavior, and interactivity of the diagrams, while Excalidraw focuses more on the simplicity of drawing with limited customization.
5. Integration Capabilities: JointJS offers seamless integration with third-party libraries and frameworks like Backbone.js and AngularJS, while Excalidraw is more standalone and does not have as many integration options.
6. Price: Excalidraw is free and open-source, available to use without any cost, while JointJS has a commercial license with pricing based on the number of developers and deployment environments.

In Summary, the key differences between Excalidraw and JointJS lie in their user interface, collaboration features, export options, customization abilities, integration capabilities, and pricing models.