Compare Revision with Published Page

Hmm, interesting feature. I agree it’d be a cool to have this. Will add it to my list, but unfortunately can’t investigate it for another few weeks at least.

I have done it for one of my projects. I hope this code help you:

<?php

if ( is_admin() && apply_filters( 'revisionize_user_can_publish_revision', current_user_can( 'publish_posts' ) || current_user_can( 'publish_pages' ) ) ) {
	add_action(
		'admin_menu',
		function () {
			add_posts_page(
				'Revision difference',
				'Revision difference',
				'manage_options',
				'revision-difference',
				'render_revision_difference_page'
			);
		}
	);

	add_action(
		'post_submitbox_start',
		function () {
			$parent = get_post( get_post_meta( get_the_id(), '_post_revision_of', true ) );

			if ( $parent && get_the_ID() !== $parent->ID ) : ?>
				<p>
					<?php
					printf(
						'<a href="%s&original_post_id=%s&revised_post_id=%s&_wpnonce=%s" target="_blank"><strong>Show differences</strong></a>',
						esc_url( menu_page_url( 'revision-difference', false ) ),
						esc_attr( $parent->ID ),
						esc_attr( get_the_ID() ),
						esc_attr( wp_create_nonce( 'revision-difference' ) )
					);
					?>
				</p>
			<?php
			endif;
		}
	);
}

/**
 * Render admin page for revision differences
 */
function render_revision_difference_page() {
	if ( empty( $_GET['original_post_id'] ) && empty( $_GET['revised_post_id'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( sanitize_key( $_GET['_wpnonce'] ), 'revision-difference' ) ) {
		wp_die( 'You can not access this page directly.' );
	}

	$original_post_id = sanitize_text_field( wp_unslash( $_GET['original_post_id'] ) );
	$revised_post_id  = sanitize_text_field( wp_unslash( $_GET['revised_post_id'] ) );

	if ( ! is_numeric( $original_post_id ) || ! is_numeric( $revised_post_id ) ) {
		wp_die( 'URL is malformed.' );
	}

	require ABSPATH . 'wp-admin/includes/revision.php';

	global $title;

	?>
	<h1><?php echo esc_html( $title ); ?></h1>
	<?php

	$revision_data = wp_prepare_revisions_for_js(
		get_post( $original_post_id ),
		$revised_post_id,
		$original_post_id
	);

	foreach ( $revision_data['diffData'] as $posts ) {
		foreach ( $posts['fields'] as $field ) {
			?>
			<h3><?php echo esc_html( $field['name'] ); ?></h3>
			<?php
			echo $field['diff'];
		}
	}
}

@novecode this is so far working great, yet it does not work with ACF, is there a simple way to make the ACF fields show up?