1. User Interface: Gmail has a clean and minimalist interface with a focus on ease of use, while Microsoft Outlook has a more business-like appearance with a complex and feature-rich interface. Outlook provides more customization options, such as creating categories and folders, while Gmail is more streamlined and straightforward in navigation.

2. Storage Capacity: Gmail offers a generous storage capacity of 15 GB for free users, whereas Outlook only provides 5 GB. Additionally, Gmail allows users to purchase additional storage if needed, while Outlook requires users to upgrade to a premium plan for more storage space.

3. Integration with Other Services: Gmail seamlessly integrates with other Google services such as Google Calendar, Google Drive, and Google Meet, providing a comprehensive suite of tools. On the other hand, Outlook is deeply integrated with Microsoft Office applications like Word, Excel, and PowerPoint, offering a cohesive experience for users who heavily rely on Microsoft products.

4. Search Functionality: Gmail's search function is known for its speed and accuracy, allowing users to quickly find specific emails or attachments. In contrast, Outlook's search function is deemed less efficient and sometimes requires more specific keyword inputs to yield relevant results.

5. Filtering and Organization: Gmail offers robust filtering options that automatically categorize emails into Primary, Social, Promotions, Updates, and Forums tabs, helping users to prioritize their emails. Outlook relies more on manual folder organization and rules for sorting emails, requiring users to set up filters and rules to achieve a similar level of organization.

6. Collaboration Features: Gmail emphasizes collaboration through features like Google Drive integration, real-time document editing, and easy sharing options. Microsoft Outlook, on the other hand, provides collaborative tools through its integration with Microsoft Teams, offering a platform for team communication and collaboration within the email interface.

In Summary, Gmail and Microsoft Outlook differ in user interface, storage capacity, integration with other services, search functionality, filtering and organization options, and collaboration features.