What is the difference between header and title of a document in HTML.

Answer 1

Document title is the text shown in browser title bar when the page is loaded in. Commonly used as brief intro or description about the document content.

As for header, we got that covered in HTML tutorial

https://www.sololearn.com/learn/HTML/2199/

Answer 2

From what I know Header is for the navigation, If you have elements that should be at the Top like your logo of the Website you put it in Header.
Title is, what should be shown on a tab for your website... For example your tab without a Title looks like this: http://localhost/MyWebsite

With Title: MyWebsite

So you see the second on is easier to understand for visitors.

For more information go to w3schools.com