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Your question is vague, but I will answer to the best of my ability.

Each school offers some minor differences in terms of quests (School spell quests and school pet quests), so you will have a slightly different experience in questing than your other wizard, and it is always fun to explore the different quests offered for different schools. In my opinion, there is not near enough distinction between the experience between schools and there should be more school specific quests, but there are at least a few that will make the game a tad different for each school.

Obviously, combat is a major change. Each school has a certain tactic in combat. With you being balance, I would guess you would blade and trap for your teammates a lot, as well as possibly tank every now and then. That could completely change depending on what school you choose. For example:
Ice is the primary class for tanking due to their extremely high health. You will often find Ice wizards going into battle first so they can take most of the major damage. Ice has very low damage though.
Storm on the other hand is a powerhouse. It is meant to be the major hitter of a team, but it also has very low health, meaning Storm is definitely not meant to tank.
So strategy changes from school to school. And obviously, your spells will change as well, and it is always fun to use new and different spells.

In my opinion, it is worth going through the game again. I know some people who have gone through the game, no joke, twelve times across two accounts. I have only gone through the game twice, myself. Also, when you go through the entire game intentionally with a specific two or three friends, it is ALWAYS more fun, because you have a specific strategy you use together through the entire game and it can make things easier. If you want good and easy strategy through your play through, I advise instead of death, you should be a Storm. That way you have a hitter (Storm), a tank (Ice), and a healer (Life)!