Get her a "gift certificate" or "IOU" for a bike - don't buy one without her trying it. Don't focus on "women's specific" - focus on fit. I am 5'2" and ride a not-WSD bike.
That said, women's bikes usually have
- shorter top tube
- taller head tube
- women's saddle
- narrower handlebars
- shorter reach brake levers (not often)
The important part is top tube fit, and just plan on having to do some saddle trial and error.