A Scout is thrifty! Sounds like a great plan. You will want to read (edit - RS) about the two requirements where I noticed changes since she will have to use those updated requirements when ranking up.
I have the new book in my hands because the Scout Shops are now selling them, which is a bit earlier than I had hoped. A quick rundown of the changes:
All images of Scouts were updated to be girls. Several other photos containing people were changed to use females or are simply different. They still all have the same theme and often very similar poses.
Colors behind headers, like section headings, have changed. The white text is more readable because the backgrounds are darker.
Boy Scouts, when referring to the program, now typically says Scouts BSA. When referring to the individual, it is now Scout.
The youth protection booklet in the front has more content. Likewise the safety chapter has much more about sexual abuse, plus the topics were slightly rearranged. Two pages were added here about dangers, warning signs, and what to do.
I could find no updated hygiene section. Everything there looked the same. The instructions for tying a necktie are still in the book too.
Structurally the books are identical up to chapter 13. That means each page in the 13th edition looks identical to the 14th edition. As mentioned earlier, there is more content in chapter 13, so chapter 14 starts on page 412 instead of 410, and we are back to nearly identical content. If you refer to any page before 396, those page number references, paragraphs and sentences are still spot-on.
The only changes I noticed in the rank requirements were for Second Class 1b and First Class 1a. They seem to have relaxed the requirement a tiny bit, though I suspect the boys edition will have the same wording.
Second Class 1b: "Since joining Scouts BSA, participate in five separate troop/patrol activities, at least three of which must be held outdoors. Of the outdoor activities, at least two must include overnight camping. These activities do not include troop or patrol meetings. On campouts, spend the night in a tent that you pitch or other structure that you help erect, such as a lean-to, snow cave, or tepee. (See pages 260 and 276-277.)"
First Class 1a has 10 activities, six outdoors and three overnight camping. The rest is the same
Oh that brings up another change. The requirements all now have page numbers listed for relevant information.
I may have missed some stuff, but I did page through it for the past two hours and that was everything I saw. Overall I am very pleased with this book.