CrazyRedHead perhaps doesn't realize what postgraduate work in engineering is like. It certainly isn't about completing classes only, and research and completing a thesis is completely necessary to get an MSc/MASc or PhD in engineering. While it is more applied, it is still very rooted in theoretical science, and independent research is done in engineering postgraduate study. It isn't necessarily easier or more difficult than a science postgraduate degree.
Applied physics Ph.D. is basically an engineering degree. It teaches physics principles in an applied manner. Therefore, this degree would be used in application working with companies or universities. It is extremely closely related to an engineering doctrate. A Ph.D. in physics is taught in theoretical terms. This teaches you basics and allows you to explore more. This would be a Ph.D. for theoretical scientists, astronomers, geologists, etc. This degree is meant to train you to research on your own.
What would be harder? A Ph.D. in physics would be, hands-down. Applied physics would be more focused on completing classes, and physics would be focused on you making a thesis. A Ph.D. in physics would no doubt be harder to get into, as well. An applied physics Ph.D. would simply look at how many classes you've done; a physics Ph.D. would look at how much of your own research you are capable of.