using have post or while post in wordpress code example

Example 1: wordpress the loop

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>

      <h2><?php the_title(); ?></h2>
      <?php the_content(); ?>

    <?php endwhile; else: ?>

      <h2><?php esc_html_e( '404 Error', 'phpforwp' ); ?></h2>
      <p><?php esc_html_e( 'Sorry, content not found.', 'phpforwp' ); ?></p>

<?php endif; ?>

Example 2: php if have post

<?php 
if ( have_posts() ) {
	while ( have_posts() ) {
		the_post(); 
		//
		// Post Content here
		//
	} // end while
} // end if
?>