HTML is also known as the HyperText Markup Language. This is the way that the different web pages and online websites that you see online are coded to make sure that the web pages can be viewed properly by people. Plain text is known to be regular text.
This may be the content that you are going to place on your website that will be properly arranged depending on the HTML that you will use. Plain text does not come with any options that will allow you to format your text. It will be very simple and it will also come with no frills to use. HTML will require knowledge and certain skills so that you can do it properly.