What is the difference between React Element and React Component?

An Element is a plain object describing what you want to appear on the screen in terms of the DOM nodes or other components.

Elements can contain other Elements in their props. Creating a React element is cheap. Once an element is created, it is never mutated.

The object representation of React Element would be as follows:

const element = React.createElement(
  'div',
  {id: 'login-btn'},
  'Login'
)

The above React.createElement() function returns an object:

{
  type: 'div',
  props: {
    children: 'Login',
    id: 'login-btn'
  }
}

And finally it renders to the DOM using ReactDOM.render():

<div id='login-btn'>Login</div>

Whereas a component can be declared in several different ways. It can be a class with a render() method. Alternatively, in simple cases, it can be defined as a function. In either case, it takes props as an input, and returns a JSX tree as the output:

const Button = ({ onLogin }) =>
<div id={'login-btn'} onClick={onLogin}>Login</div>

Then JSX gets transpiled to a React.createElement() function tree:

const Button = ({ onLogin }) => React.createElement(
  'div',
  { id: 'login-btn', onClick: onLogin },
  'Login'
)