1. Cost: MailHog is an open-source software that is completely free to use, while Mailtrap offers both free and paid plans. The free plan of Mailtrap has limitations on the number of emails that can be sent and stored, while the paid plans offer higher limits and additional features.

2. Email Storage: MailHog is designed for local email testing and does not provide storage for emails indefinitely. On the other hand, Mailtrap offers a cloud-based platform that provides long-term email storage, ensuring that your email communication history is retained.

3. Integration Options: MailHog primarily acts as a local testing tool that captures emails sent from local applications or servers. It does not provide direct integration with popular software development tools or frameworks. Mailtrap, on the other hand, offers seamless integration with various frameworks, programming languages, and service providers, making it easier to incorporate it into your existing development workflow.

4. Collaboration and Sharing: MailHog does not offer collaboration features, making it difficult to share emails with team members or clients. In contrast, Mailtrap provides collaboration tools to share email inboxes with multiple users, allowing seamless collaboration and feedback on email content.

5. Advanced Features: MailHog is a basic testing tool that captures emails and provides a simple UI for viewing them. It does not offer advanced features like spam analysis, email tracking, or HTML rendering. Mailtrap, on the other hand, includes advanced features such as spam testing, email tracking, HTML rendering, email analytics, and more, enabling thorough testing and analysis of emails.

6. Support and Documentation: As an open-source software, MailHog relies on its community for support and documentation. While it has an active community, the level of support may vary. Mailtrap, on the other hand, offers dedicated customer support and comprehensive documentation, ensuring that users receive timely assistance and have access to the necessary resources.

In Summary, MailHog is a free open-source local testing tool with limited features and no long-term email storage, while Mailtrap offers a more comprehensive solution that includes advanced features, collaboration options, and dedicated support.