I just found this. Sadly, I can't fully answer the question. But I can give you a "sort of" answer.
I own the BR heritage "slouchy skinny" from several years ago. I bought it a size bigger than my usual size at the Gap, but not on purpose. This was right after weight loss. I couldn't believe that I could fit into this size -- sizing had changed so radically. Anyway...it fit like a skinny on my not-skinny calves but had slouch and give and a bit of waist looseness. I am probably wearing it a bit more "slouchy" than intended, in other words. But it works for me.
I'll bet the sizing is pretty similar.