Express.js vs. Pure Node.js for Web Application Development

I’m relatively new to web development, and I’m trying to understand the differences between using Express.js and pure Node.js for building web applications. I’ve heard that Express.js is a popular framework built on top of Node.js, but I’m not sure when I should choose one over the other.
Here are my questions:

  1. What are the key differences between Express.js and pure Node.js for web development?
  2. When is it advantageous to use Express.js, and when should I consider using pure Node.js?
  3. Are there specific types of web applications or use cases where one choice is more suitable than the other?
  4. Are there performance considerations or scalability differences between the two approaches?
  5. Are there any notable features or libraries in Express.js that significantly simplify web development compared to pure Node.js?

I’d welcome advice from seasoned engineers who have worked with both Express.js and pure Node.js, as well as any code examples or real-world scenarios that emphasize the advantages of both methods. I’ve looked at a number of sources but have yet to find a suitable answer. We appreciate you sharing your knowledge.