Yaoi versus M/M Romance: What's the difference? Is there a difference?

*Pic courtesy of Homotography
So before I begin this discussion, I suppose I need to define what constitutes "M/M Romance" and "Yaoi". Of course, by setting a definition I may very well answer my original question;) But here goes:

M/M Romance: This is usually defined as women writing homoerotic romances for women. It usually comes in book form - short stories, novellas or novels. The covers of the books are made up of largely  half nude, buffed men. The covers are also done with photo-manipulat...