Historical Fiction v. Historical Romance

I had an interesting phone conversation with a friend this morning who doesn't typically read romance, but has really been enjoying my books. She is, however, a historical fiction reader. We got into a discussion about the differences between the two--which at time, admittedly, can be difficult to qualify (Outlander comes to mind, as do Katherine, or The Other Boleyn Girl). In general, I think romances focus on the relationship whereas in historical fiction, the romance is just one of the plot threads. I read both, and I guess I've always assumed that readers of historical romance probably also read historical fiction (although not necessarily the other way around) but maybe I'm wrong. Not surprisingly though, my favorite historical fiction books have a strong romance plot.

Since you are reading this blog, I figure it's a good bet that you read historical romance...but do you also read historical fiction? (Phillipa Gregory, Sharon Kay Penman, Dorothy Dunnett, Anya Seton, Elizabeth Chadwick, etc). What about Gabaldon . . . do you consider her books romances or historical fiction?