Tobias Nyholm

Prevents an user to publish a post without a thumbnail. If a user presses the publish button without a thumbnail, the post will 
be saved as a draft. For more information see installation page or the 
<a href="http://www.webfish.se/wp/plugins/require-thumbnail" title="Webfish - WordPress plugin" rel="nofollow ugc">Webfish</a> homepage.

Require Thumbnail

Prevents an user to publish a post without a thumbnail.

Rafa Poveda

Mecus Consultores

Rocio Valdivia

The plugin gives the option to select the size of the post thumbnail in the feed as:
<ul>
<li>Thumbnail</li>
<li>Medium</li>
<li>Large</li>
<li>Full</li>
</ul>
To change the size of those images, you can do it in Settings -> Media ( http://example.com/wp-admin/options-media.php )

Post Thumbnails in Feed

Adds your post thumbnails to your feed and select the post thumbnail size to show.

Require Thumbnail vs Post Thumbnails in Feed