1. Routing Mechanism: Tornado uses a flexible routing mechanism with regular expressions for defining URL handlers, allowing for more complex and dynamic routing patterns. On the other hand, webapp2 uses a simpler routing system with a predefined set of route patterns, making it easier to set up basic routing configurations.

2. Asynchronous Support: Tornado is designed to handle asynchronous operations efficiently, making it suitable for applications that require high-performance and real-time capabilities. In contrast, webapp2 does not natively support asynchronous operations, which can limit its scalability for certain types of applications.

3. Templating Engine: Tornado provides its own built-in templating engine called Tornado Templates, which is more flexible and powerful for managing and rendering dynamic content. Webapp2, on the other hand, relies on external templating engines like Jinja2 for handling template logic, making it less integrated in comparison.

4. Middleware Support: Tornado offers a comprehensive middleware system for easily adding application logic and processing requests at various stages of the HTTP pipeline. Webapp2, while supporting middleware functionality, does not provide as extensive options for customizing request processing flow through middleware components.

5. Community and Ecosystem: Tornado has a smaller community and ecosystem compared to webapp2, which is part of the larger Google App Engine framework. This can impact the availability of libraries, plugins, and resources for developers using Tornado, potentially requiring more custom development work for certain features.

In Summary, the key differences between Tornado and webapp2 lie in their routing mechanisms, support for asynchronous operations, templating engines, middleware capabilities, and the size of their respective communities and ecosystems.