Deno is a new runtime environment for JavaScript and TypeScript, designed to be more modern and secure than Node.js. It was created by Ryan Dahl, the founder of Node.js, with the goal of building a more user-friendly non-blocking framework. Deno has several key differences from Node.js, including support for TypeScript out of the box, asynchronous main functions, and security features such as no access to the file system or network by default. Deno also uses the V8 JavaScript engine and is built with Rust. The project doesn't include a package.json file or node_modules directory, and instead relies on native ECMAScript modules for dependencies. To find external libraries for Deno, one can use the official Deno modules repository or Skypack, a content delivery network for code. The underscore.js library can be used to compare objects for equality. Deno has several unique features, including the ability to run applications directly from a specified URL and support for command-line arguments. It also allows developers to create a program that compares objects for equality using pure TypeScript and the underscore.js library.