The Virtual DOM and the actual DOM are two different representations of the same underlying structure of a web page.

  The actual DOM, or Document Object Model, is a tree-like structure that represents the HTML elements of a web page. It is the browser's internal representation of the page's structure and content. The actual DOM is directly manipulated by JavaScript to add, remove, or modify elements, styles, and attributes. Any changes made to the actual DOM trigger re-rendering and layout calculations, which can be computationally expensive.

  On the other hand, the Virtual DOM is a concept that involves creating a lightweight copy of the actual DOM in memory and using it as an intermediary between JavaScript logic and the actual DOM. The Virtual DOM is a JavaScript object that simulates the structure and properties of the actual DOM elements. It allows developers to perform operations on this virtual representation without affecting the actual DOM.

  The main advantage of the Virtual DOM is its ability to perform efficient updates. Instead of directly modifying the actual DOM, changes are first applied to the Virtual DOM. The Virtual DOM then calculates the difference between the previous and new state of the application and efficiently updates only the necessary parts of the actual DOM. This process is known as reconciliation and it greatly reduces the number of manipulations needed on the actual DOM, resulting in improved performance.

  By abstracting the actual DOM into a virtual representation, the Virtual DOM enables developers to write their applications in a more declarative and component-based way. Updates to the application state are handled through the Virtual DOM, which makes it easier to reason about and maintain the codebase.

  In summary, the main difference between the Virtual DOM and the actual DOM is that the Virtual DOM is a lightweight copy of the actual DOM that allows for efficient updates and abstraction of the actual DOM, making it easier to develop and maintain complex web applications.