1. Performance: Dapper is known for its excellent performance and is optimized for high-speed data access. It uses a lightweight and minimalistic approach for mapping database rows to objects, allowing for faster execution and lower memory consumption. On the other hand, GORM is a full-featured ORM (Object-Relational Mapping) that offers a wide range of features but might not perform as efficiently as Dapper in certain scenarios.
2. Language Support: Dapper is primarily designed for the .NET framework and is widely used with C#. It provides seamless integration with C# code and has specific extensions for popular .NET languages. Conversely, GORM is specifically built for the Go programming language and follows Go's idiomatic style. It provides robust support for Go's concurrency features and leverages its functionality for a smoother development experience.
3. Querying Approach: Dapper focuses primarily on providing support for raw SQL queries. It allows developers to write their SQL queries directly and maps the results to objects without any complex abstraction layer. On the other hand, GORM provides a more abstract and higher-level querying approach. It offers a wide range of query methods and supports dynamic query building using chained method calls. This allows developers to write complex queries without explicitly writing raw SQL statements.
4. Database Support: Dapper works with a variety of databases, including SQL Server, MySQL, Oracle, SQLite, and PostgreSQL, among others. It provides consistent support for different database providers and allows developers to leverage specific features offered by each database. Conversely, GORM is primarily optimized for working with relational databases, such as MySQL, PostgreSQL, and SQLite. Although it can work with other databases through plugins, its core functionality is designed for relational databases.
5. External Dependencies: Dapper is a lightweight library with minimal dependencies. It has no external dependencies outside of the .NET framework, making it easy to integrate into existing projects. In contrast, GORM has a higher number of external dependencies, as it relies on various Go libraries to provide its extensive functionality. While these dependencies enhance GORM's feature set, they may introduce additional complexity and versioning issues during project setup and maintenance.
6. Community and Support: Dapper has a large and active community of developers who actively contribute to its development and maintenance. It has been around for a longer time and has gained widespread adoption in the .NET ecosystem. GORM, on the other hand, is relatively newer, but it is backed by a growing community of developers who are actively improving and expanding its features. While both frameworks have their respective communities, Dapper's larger community may provide more readily available resources and support.

In summary, Dapper and GORM have key differences in terms of performance, language support, querying approach, database support, external dependencies, and community and support. Dapper focuses on speed and efficiency with its minimalistic approach, while GORM offers a full-featured ORM with a higher-level querying approach. The choice between the two depends on specific requirements and preferences of the development project.