HTML or Hypertext Markup Language is a markup programming language. This task is particularly designed for the layout of the web pages. HTML is a programming language that constructs a web browser or renders the page into a pretty web page. So, HTML is always used with CSS.
PHP is a server-side programming language. PHP is able to process the request & generate the HTML to display the client or web browser. PHP is capable of managing & handling a lot of varying information along with managing complex data structures, performing calculations, looking up bulk information in databases & much more.
When we compare two programming languages, HTML is definitely an easier programming language to learn & execute. Most programmers suggest to initiate the learning of program languages with HTML & later on move to the PHP language part since PHP is a huge independent concept when we look upon building the website or web pages. The path one must follow is HTML, CSS, JavaScript, Node JavaScript, Python or PHP. JavaScript is known for giving elegance to the website. It helps us to make beautiful web pages with HTML & CSS languages.