1. Integration: Chart.js is specifically designed for creating various types of charts such as line, bar, pie, etc., while Hammer.js is a library that enables gestures recognition on touch devices. The key difference between the two is their primary focus, where Chart.js is aimed at data visualization, and Hammer.js is for touch gestures.

2. Functionality: Chart.js is used to create interactive and visually appealing charts to present data effectively, whereas Hammer.js focuses on providing touch interactions like tap, swipe, pinch, rotate, etc., making web applications more user-friendly. These differences in functionality cater to distinct development needs and goals.

3. Usage: Chart.js is commonly used in data-driven web applications and dashboards to showcase information in a graphical format for better understanding, whereas Hammer.js is employed in mobile web development to enhance touch interactions and provide a seamless user experience on touch-enabled devices. The usage of these libraries is dictated by the requirements of the specific project.

4. Dependencies: Chart.js has dependencies on Moment.js for date formatting and parsing, which may need to be included additionally based on the chart requirements. On the other hand, Hammer.js has no external dependencies and can be directly integrated into projects without requiring any other libraries. This difference in dependencies affects the ease of integration and overall project setup.

5. Customization: Chart.js allows for extensive customization of charts with various configuration options for colors, labels, tooltips, animations, etc., providing flexibility in design. In contrast, Hammer.js focuses on predefined touch gestures and lacks extensive customization options, as its main purpose is gesture recognition and not visual design customization.

6. Community Support: Chart.js has a strong community backing with regular updates, extensive documentation, and a plethora of resources available for developers to troubleshoot and enhance their chart creations. While Hammer.js also has community support, it may not be as extensive or as frequently updated as Chart.js due to the specific nature of touch gesture recognition. This disparity in community support can affect the availability of resources and assistance for developers using these libraries.

In Summary, Chart.js and Hammer.js differ in their integration focus, functionality, usage scenarios, dependencies, customization options, and community support, catering to distinct needs in data visualization and touch interaction development.