Ask HN: What is the difference between a devops and an infrastructure engineer?

Recently I wrote a blog post about my internship at a startup in Egypt ( http://blog.mbassem.com/2015/02/04/my-journey-with-trustious/ ) that helped me find my passion. I knew the kind of work I love but I can't find a suitable title for it. I think it's either an infrastructure engineer or a devops engineer. So I would love to know the difference between both of them from the requirements and responsibilities point of view. Thank you.