Difference?

There are a lot of differences. There are some new weapons/armors, as well as some changes to existing ones. Some magics have been altered, both in how they work and how they are acquired (Some magics and techniques you have to find in chests, rather than being able to buy them all). The biggest change is evident in the title. Rather than have a single full license board for every party member, in IZJS you have to choose a license board for each character. Each different license board is associated with a different job/class (ie White Mage, Black Mage, etc.). This also means that you won't be able to learn every spell and technique with every character, and each license board unlocks different types of weapons that can be used for that character (meaning that a Black Mage won't be using swords or spears, and a Samurai can't use things like guns, staves, etc. They are specific to their job). There are a few other changes as well, such as the ability to speed up the game (fast mode) by pressing L1. This makes passing over a large area and fighting battles much quicker.