A Big Day for Little Jack

I've put these books together for review because their subject-matter is so similar and is an important one for young children. Both books deal, very sensitively and interestingly, with a small child's fear of taking steps into the outside world. They show how a loved toy can act as a catalyst and support by projecting the child character's fears onto the toy.
The first tells of a little girl who is nervous of the big playground in the park with its slide and swings and bigger, bolder children. The second is about a little rabbit asked to his first party and frightened of going alone. Perhaps there is rather too easy a solution implied in both books but small children will identify with, and find comfort in, the stories, while parents might find ideas for helping a shy child to find friends and social skills. A question for the publisher - both books were published at the same time and are the same size; I wonder why the price difference?