In addition, TAH has a little more variety in its pages, and adds a noisy dragonfly who's hidden on each page. One of your goals then becomes to find where the dragonfly is hiding. Broderbund has tried to vary the formula a little within the Living Books genre, with mixed results. The drawings are mostly pencil-like, meaning there's a lack of color. And because there's not much in the way of background, there don't appear to be as many hidden animations as the other books.
Different books purport to appeal to different audiences.
RUFF'S BONE is, I believe, the first original story published by Broderbund, and is one of the newest titles, so perhaps they're starting off in a new direction. Well, there isn't really one. I think these are great products. If there would be any downside, it might be the long-term play value of the Living Books. After your child spends about two weeks of intensive exploring, there's not much to find.