I don't think I'd call any anime that isn't hentai as ero-anime, no question.
But there are animes that are considered ecchi and that doesn't include all romance titles. If you can put that distinction based on content into visual novels you get my distinction between a visual novel that are also eroge, and a visual novel that isn't.
These titles that are both visual novels and eroge, I usually refer as visual novels, but I won't exclude them from eroges, because I measure them in different ways.
For me what makes a visual novel a visual novel is not the content, but the medium, story (in NVL or text box) with choices. What makes an eroge is the content.