What is the Difference Between Assembly and DLL?

The main difference between an assembly and a DLL lies in their purpose, usage, and internal structure. Here are the key differences between the two:

1. Purpose:

• An assembly is a precompiled chunk of .NET code that can be run by the Common Language Runtime (CLR). It serves as a single unit of deployment for .NET applications.
• A DLL (Dynamic Link Library) is a shared library implementation developed by Microsoft, which contains a collection of resources that can be used to develop applications.

1. Usage:

• An assembly can be an executable (EXE) or a dynamic link library (DLL).
• A DLL is a dynamically linked library that can be used by any program running on Windows, providing a collection of methods and classes that can be reused by other applications.

1. Internal Structure:

• Assemblies are physically similar to DLLs, but they have many internal differences.
• DLL files have code sections that are shared and data sections that are private, meaning all processes using the DLL will use the same copy of the code, while each process will have its own copy of the data.

1. Deployment:

• Assemblies are the fundamental units of deployment, version control, reuse, activation scoping, and security permissions for .NET-based applications.
• DLLs are library files that are linked dynamically, often used in conventional Windows programming.

In summary, an assembly is a precompiled code unit used by .NET applications, while a DLL is a shared library implementation used by Windows applications. Assemblies are the building blocks of .NET applications and serve as a single unit of deployment, while DLLs provide a collection of resources that can be reused by other applications.

Comparative Table: Assembly vs DLL

Here is a table comparing the differences between an assembly and a DLL:

In summary, an assembly is a specific type of file used in .NET applications, containing compiled code and metadata, while a DLL is a general-purpose library containing code and data. Assemblies are the smallest unit of deployment for .NET applications, and they can reference other assemblies, whereas DLLs can be referenced by multiple applications and can be deployed at different levels.