Trello is a flexible Kanban board that can be used to track any kind of project, big or small, and offers a fast and loose approach to productivity with its cork-board-like interface. It's easy to use, has unlimited cards on up to ten boards per workspace in its free plan, and is suitable for teams of any kind to manage almost any type of project. On the other hand, Jira is a more structured tool that offers different Agile workflows, including Scrum, and provides features like time tracking and reports, making it a great collaboration tool for Agile software development teams. While both apps have overlapping features, Trello's free plan is more generous, and its flexibility makes it suitable for a wider range of projects. Ultimately, the choice between Trello and Jira depends on the specific needs of the team or project.