1. User interface: The user interfaces of Confluence and Mattermost are quite different. Confluence has a more visually appealing and user-friendly interface, with features like live editing and document previewing. On the other hand, Mattermost has a more minimalist interface focused on chat and collaboration, with options for customizing the theme and layout.
2. Collaboration features: Confluence provides advanced collaboration features such as real-time editing, version history, commenting, blogging, and task tracking that allow teams to work together seamlessly. Mattermost, on the other hand, focuses primarily on instant messaging and team communication, with features like channels, direct messaging, and file sharing.
3. Document management: Confluence is specifically designed for creating and organizing documents. It provides a centralized platform for creating, formatting, and storing documents, with options for organizing them into hierarchical structures. Mattermost, however, does not have built-in document management capabilities and is primarily intended for real-time communication rather than document collaboration.
4. Integration capabilities: Confluence offers a wide range of integrations with other tools and platforms, allowing users to connect and collaborate across different systems. It seamlessly integrates with tools like JIRA, Trello, Salesforce, and more. While Mattermost also provides integration options, they are generally more limited in scope and focus mainly on integrating with development tools like GitLab and GitHub.
5. Access control and permissions: Confluence provides comprehensive access control and permission settings, allowing administrators to define fine-grained roles and permissions for different user groups. This ensures that sensitive information and documents are accessible only to authorized individuals. Mattermost, on the other hand, has more limited access control capabilities, with options to configure basic team-wide permissions and channel-specific access settings.
6. Pricing and deployment options: Confluence is a commercial product that requires licensing, with pricing based on the number of users and deployment options available as both cloud-based and self-hosted. Mattermost, on the other hand, offers a free self-hosted version as well as a paid commercial version with additional features and support. It provides more flexibility in terms of deployment options, including on-premises, cloud, and hybrid configurations.

In Summary, Confluence is a comprehensive document collaboration platform with advanced features, a visually appealing interface, and extensive integration capabilities, while Mattermost is focused primarily on real-time communication with a minimalist interface and more limited document management capabilities.