My understanding is that they are similar but cacao powder hasn't gone through dutch processing which neutralizes the acids. Here's a link for a better explanation of natural versus dutch processed
http://www.joyofbaking.com/cocoa.html#ixzz1FSltJ9zn The recipes I've seen for cacao have been for smoothies or raw vegan desserts. Some believe that cooking destroys the nutritional benefits of cacao. I can't have chocolate so I haven't worked with cacao.