ASP.NET Core is a significant redesign of the traditional ASP.NET framework. While both frameworks are used for building web applications, they differ in several key areas, including architecture, performance, platform support, and development experience. Below, we explore these differences in detail.

1. Cross-Platform Support

ASP.NET Core: It is designed to be cross-platform, meaning it can run on Windows, macOS, and Linux. This allows developers to build and deploy applications on various operating systems.

Traditional ASP.NET: It is primarily Windows-based and runs on the Internet Information Services (IIS) server, limiting its deployment options.

2. Modular Architecture

ASP.NET Core: It follows a modular architecture, allowing developers to include only the necessary components and libraries for their applications. This results in smaller application sizes and improved performance.

Traditional ASP.NET: It is monolithic, meaning that it includes a large set of libraries and components by default, which can lead to larger application sizes and potentially slower performance.

3. Performance

ASP.NET Core: It is built for high performance and is optimized for handling a large number of requests efficiently. It uses the Kestrel web server, which is lightweight and fast.

Traditional ASP.NET: While it performs well, it is generally slower than ASP.NET Core due to its older architecture and reliance on IIS.

4. Dependency Injection

ASP.NET Core: It has built-in support for dependency injection, making it easier to manage dependencies and improve testability. This is a core feature of the framework.

Traditional ASP.NET: Dependency injection is not built-in and requires additional libraries or frameworks to implement.

5. Unified Framework

ASP.NET Core: It unifies the MVC and Web API frameworks, allowing developers to use a single framework for both web applications and APIs. This simplifies development and reduces the learning curve.

Traditional ASP.NET: It separates MVC and Web API into different frameworks, which can lead to redundancy and increased complexity.

Sample Code Comparison

ASP.NET Core Example

        
            // ASP.NET Core Controller
            using Microsoft.AspNetCore.Mvc;

            public class HomeController : Controller
            {
                public IActionResult Index()
                {
                    return View();
                }
            }
            

Traditional ASP.NET Example

        
            // Traditional ASP.NET Web Form
            using System;
            using System.Web.UI;

            public partial class Home : Page
            {
                protected void Page_Load(object sender, EventArgs e)
                {
                    Response.Write("Hello, World!");
                }
            }
            

6. Configuration and Startup

ASP.NET Core: It uses a simplified configuration model that allows for easy setup and customization. The configuration can be done using JSON files, environment variables, and command-line arguments.

Traditional ASP.NET: Configuration is typically done through XML files (like web.config), which can be more cumbersome and less flexible.

Conclusion

ASP.NET Core represents a modern approach to web development, offering numerous advantages over the traditional ASP.NET framework. Its cross-platform capabilities, modular architecture, and built-in features like dependency injection make it a powerful choice for developers looking to build scalable and maintainable applications.