The difference between yaoi and bl

I spent my morning blog surfing and happened upon the Yaoi Review. The webmaster restructured the way she does reviews on her site. There are four categories she grades: plot/readability, character development, illustrations, and sexual explicitness. The fact sexual explicitness is given its own section made me think about how many fans in the US think of sex when they think of BL. Why is this?

The majority of BL fans in the US didn't start out reading BL. Yaoi came first. With yaoi comes the expectation of sex. When fans move onto BL the expectation carries over. Because of this the line between Yaoi and BL has been muddled and mixed up to the point where the two words are used interchangeably. Or, in most cases, BL isn't used at all.

I don't have a problem with US fans calling BL yaoi. However, I think it is important for fans to know the difference between fan made works and professional ones. Yes, you can find BL manga where the whole purpose is to titillate, but this is also true of shoujo and shounen. Sex isn't tied to those genre's. Sex shouldn't be tied to BL.