Serendipitous timing - this article was posted yesterday about using mark-up, and how Open Graph and Schema.org are used, and why to use both:

Facebook Open Graph serves its purpose well, but it doesn’t provide the detailed information search engines need to improve the user experience. A single web page may have many components, and it may talk about more than one thing. Even if you mark up your content for Facebook Open Graph, schema.org provides an additional way to provide more detail about particular entities on the page.

http://searchengineland.com/schema-org-7-things-for-seos-to-consider-post-hummingbird-172163