what is a tag and and an element

Answer 1

<h1> and </h1> are html tags.
"<h1>Some Heading</h1>" the whole thing is an html element.

Answer 2

An element is an object in the webpage, while a tag is the text that defines the element, and tells the browser what kind of element it is or what kind of content it contains. @ZinC provided you a perfect example.