what is the difference between head and header tag

Answer 1

To complete @noname answer:

<header> is a visible semantical element of the page, and can be used as well to define page header than sub part headers(inside a <div>ision, a <article> and so on such containers) ;)

Answer 2

The head tags is the section of the html where you put the non visible element such as the title, scripts and style.among others.

Header in the other hand is a visible html5 element which is used to hold elements that are part of the header of the page.