time-difference-example.php

get_time_difference( $comment->comment_date );

time-difference-formatting.php

get_time_difference( '0000-00-00 00:00:00' );

time-difference.php

<?php
/**
 * Return a time difference of a given time in
 * days, hours or minutes depending on the time
 * difference.
 *
 * @param $time (required)
*/
function get_time_difference( $time ) {
	$current_time = new DateTime( current_time( 'mysql' ) );
	$previous_time = new DateTime( $time );
	$difference = $current_time->diff( $previous_time );
	$timestamp = '';

	if ( 0 < $difference->y ) {
		/**
		 * If we've passed one year, let's show the full
		 * date.
		*/
		 $timestamp = get_the_date( 'F j, Y' );
	} else if ( 12 >= $difference->m && 1 <= $difference->m ) {
		/**
		 * If we've made it here, we know that we have not
		 * yet passed one year, but have made it passed one
		 * month. As such, let's remove the year from the 
		 * output, but keep the date style format.
		*/
		$timestamp .= get_the_date( 'F j' );
	} else if ( 0 < $difference->d ) {
		/**
		 * If we've made it here, we know that we have not
		 * yet passed one month, but have made it passed one
		 * day. As such, let's show just the number of days
		 * that have passed.
		*/
		$timestamp .= sprintf( translate_nooped_plural( _n_noop( '%s Day Ago', '%s Days Ago' ), $difference->days ), $difference->days );
	} else if ( 0 < $difference->h ) {
		/**
		 * If we've made it here, we know that we have not
		 * yet passed one day, but have made it passed one
		 * hour. As such, let's show just the number of hours
		 * that have passed.
		*/
		$timestamp .= sprintf( translate_nooped_plural( _n_noop( '%s Hour Ago', '%s Hours Ago', 'listed' ), $difference->h, 'listed' ), $difference->h );
	} else if ( 0 < $difference->i ) {
		/**
		 * If we've made it here, we know that we have not
		 * yet passed one hour, but have made it passed one
		 * minute. As such, let's show just the number of
		 * minutes that have passed.
		*/
		$timestamp .= sprintf( translate_nooped_plural( _n_noop( '%s Minute Ago', '%s Minutes Ago', 'listed' ), $difference->i, 'listed' ), $difference->i );
	} else {
		/**
		 * If we've made it here, that this post is fresh
		 * off the press. Let's show how fresh it is.
		*/
		$timestamp = __( 'Just Now', 'listed' );
	}

	return $timestamp;
}