What is PDF?
PDF files are used to keep your document formatting and to keep your data safe, especially in situations when sending a file to someone. Normally files are sent in a PDF format because the model can be stored on another computer when displayed.
What is HTML?
HTML is short for Hypertext Markup Language. HTML produces electronic documents (called pages) that appear on the World Wide Web. That page has a set of links to other sites, called hyperlinks. That web page you see on the Internet is written using one or another version of HTML code.
HTML code ensures that text and images are correctly encoded so that they can be viewed as intended by your Internet browser. A browser would not be able to display text as elements or load images or other elements without HTML. HTML also provides a basic page layout to add Cascading Style Sheets to change their appearance.