Robot.txt : Robot.txt is like a guard of your website for a web crawler or search engines. It tells to web crawler or search engines that which page will be they can visit & which not. it helps to grow your website in search ranking within SEO.
XML sitemap acts as a roadmap of your website that leads Google to your website and all of your web pages. An XML sitemap is important for SEO, as it permits Google to quickly find out your web site's all necessary pages & help your website growth popularity.