Conditional logic for article with thumbnail

So ive got an idea,

I have 2 kinds of layout for my posts one with a thumbnail and one without. I can load all my posts in my index.php but I’m stuck with the if/els condition to seperate my posts

post with thumbnail:

<article>
        <div class="clearfix">
		<h1>Post with thumbnail in background</h1>
		<time>16 Januari</time>
	</div>
	<p>Post with thumbnail</p>
</article>

Post without thumbnail:

<article>
	<h1>Normal post/h1>
	<time>16 Januari</time>
	<hr>
	<p> a post without thumbnail</p>
</article>

I load all my content with this code:

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

					<article class="clearfix">
						<h1><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h1>
						<time><?php the_date('l j F'); ?></time>
						<hr>
						<?php the_content(); ?>
					</article>

					<?php
				}

			}else{
				echo '<p>No content found</p>';
			}
		?>

Anyone know how I might do this?