I actually am looking for the same thing - thanks for posting OP!
I went into a North Face store last week just to try on the youth XL vs the womens Small and womens Med. Here's what I thought: The youth XL is actually roomier than the women's small, but smaller than the women's medium. It was like it was a womens small+. It wasn't as form-fitting though, so it didn't have a ton of room on the bust, and didn't come in at the waist. It was very roomy in the shoulders though.
As for the small - it was a bit snug on me in the bust (typical, as it's large for my frame size) and in the shoulders when I put them both forward, as I would when driving. But it was comfortable enough.
As for the medium - it was ok in the bust/shoulders, but baggy below the bust and in the stomach area. It also had really long arms.
Keep in mind, I tried all these on with a shirt and blazer on under the jackets. But in winter, I would generally wear that or a bulky sweater, so I figured it was ok.
So, please TRY ON IN A STORE before you buy - you might be getting your daughter the wrong size.