What is the difference between <head> and <header> ?
head tag is a features of html where you can import js and css file and also you can write js and css code inside it. You can also put meta data information for SEO. Header tag is new features of html5 which can be use for different purpose like to put your menu bar contents.
The head tag is used for holding Meta information, title, links, etc. and is not displayed on the page. The header tag is used within the body of the website and can be used multiple times if required, e.g. to determine the top of an article.