Huge differences between the two. RAP is creating an app for diagnosing respiratory problems from a cough.
BRN is creating a computer chip that operates more like the human brain.
Both have huge potential. I only hold RAP but have my eye on BRN.
EDIT: After rereading your post seems I didn't answer it (I'm tired). You might find a better answer in the BRN forums but I think they've got partnership issues.