There is no difference. Personally I find the adult jackets a little austere for my liking. If you are going to read a kiddy book then be proud and buy the original! 
Daughter, whose book it nominally is, would go berserk if she thought I would buy her a "Child's Book"
Funny innit from 12 to 21 you try to look and be older than you are .... from 21 to 71 you try to be younger. Once past 71 you start telling everyone who'll listen how old you are ~ usually reverting to the teenage habit of adding a couple of years for effect.
