The truth is that among bikes in a given price range, especially at the low end, there just isn't that much difference from one to another. The market's very competitive, and no one can afford to put more expensive parts on a bike than everybody else does. If they spend more on something like a rear derailleur, they have to cut back on something that doesn't show, like a bottom bracket or headset.
I'd get the one that fits her best, or that feels most comfortable. As Sci-Fi said, it's really easy to swap tires, and it makes a big difference in the bike's feel, handling and versatility. I have an Atlantis, and I've done centuries with it as well as run it on fire trails, just by changing tires.