1. Key difference 1: Scalability: MySQL is a traditional relational database management system (RDBMS) that can handle small to medium-sized workloads but faces challenges when dealing with large-scale applications that require high scalability. On the other hand, Vitess is an open-source database clustering system that extends MySQL to achieve horizontal scalability, allowing it to handle massive workloads and distribute data across multiple servers efficiently.

2. Key difference 2: Sharding: MySQL lacks built-in sharding capabilities, which means that when the database grows beyond the capabilities of a single machine, it becomes challenging to scale efficiently. In contrast, Vitess provides automatic sharding, allowing it to partition the data across multiple instances and distribute the load evenly. This enables Vitess to handle larger datasets and provide improved performance compared to MySQL in a sharded setup.

3. Key difference 3: High Availability: While MySQL supports replication for achieving high availability, it requires manual configuration and management. On the other hand, Vitess offers built-in fault tolerance and resiliency, providing automatic replication and failover capabilities. This makes Vitess a more suitable choice for applications that require high availability with minimal manual intervention.

4. Key difference 4: Query Routing: In a traditional MySQL setup, the application is responsible for routing queries to the appropriate database server, leading to complex and error-prone code. Vitess, on the other hand, acts as a middleware layer that transparently routes queries based on the sharding scheme. This simplifies the application code and eliminates the need for manual query routing, making it easier to scale and manage the database.

5. Key difference 5: Online Schema Changes: Performing schema changes in MySQL can often be time-consuming and may require downtime or application-level changes. Vitess provides efficient online schema changes, allowing database schema modifications to be performed without impacting the availability of the system. This enables applications to adapt to evolving requirements without interrupting user access to the data.

6. Key difference 6: Tools and Ecosystem: MySQL has a rich ecosystem with a wide range of tools and libraries available for various purposes, such as monitoring, backup/restore, and administration. While Vitess leverages many of MySQL's existing tools, it also provides additional tools specifically designed for deploying, managing, and monitoring a Vitess cluster. These tools enhance the operational capabilities and ease the management of a Vitess-based deployment.

In Summary, MySQL lacks native scalability and sharding capabilities, requires manual configuration for achieving high availability, lacks automatic query routing, has limitations in executing online schema changes, and relies on a broader ecosystem of tools. On the other hand, Vitess addresses these limitations by providing horizontal scalability, automatic sharding, built-in high availability, transparent query routing, efficient online schema changes, and a specialized set of tools.