You've been waiting a long time for a reply. I actually tried to answer this several days ago, but a glitch erased it and I gave up. Then my workload got heavy, but I got through it, and so, here's my answer.
The main difference between first and second person narrative is the major effect it has on point of view.
First person limits you to the information available to your character, and usually, though not always, limits you to one character's point of view. If your main wish is to let your readers in on another person's point of view, this can be very powerful, edifying, and mind-expanding. It can be a powerful way of persuading children to adopt compassionate attitudes, for example towards a person whose behaviour, appearance or other characteristics might not necessarily easily endear them to the reader, or might otherwise incur judgment that the character has no right of reply. A first person account is probably best if you want to argue a particular character's problematical viewpoint. It's usually vey subjective.
Third person gives you access to the so-called omniscient view point which lets you be objective and to show your characters from a range of different viewpoints, even reporting on their private thoughts and feelings, especially about each other, which lets you reveal character in this way. The big advantage is that you can be a bit analytical, and you can get overviews of group politics and dynamics from a variety of different angles. It's most effective if you want to show interaction among many personalities rather than one personality in order to make some point, or instil sound values. Author intrusion is possible, and not always undesirable, especially in children's literature, where moral guidance or help towards a sense of humour or responsibilty may be appropiate. Depends of course on the age of the children.
There are books written on this subject, and post-modernism explores it in some very insightful ways - can't refer you off-hand - I studied it at University a few years ago. I'll see if I can look up a few titles for you, but they'll be about ten years old now and better stuff will be available now. I recall names like 'Narrative situations', and 'dynamics of point of view' - perhaps your librarian could help you. I'm too rushed now, but I hope this helps.