So, does that make me the only one who actually read Scizzoman's wall o' text? You guys should, it's very well structured and enlightening. Now that I am done glorifying his wall, it's time to get back on track.
I do plan on getting all of the compilation, including the mobile version, because I can.
FFX and FFXII both featured interesting advancement systems, in the form of the sphere grid, and the less restrictive License system, respectively. Now for a crash course on each...
Sphere Grid
After battle, characters gain AP, and when enough is accumulated, those characters gain Sphere Levels. A sort of a grid, called the sphere grid, is employed for the express purpose of utilizing said levels. Honestly, this will probably help me explain it a bit better.
http://www.gamefaqs.com/console/ps2/file/197344/20045
So, each sphere level can be used to go one space on the grid, and one space only, in either direction. Abilities are used, using a separate sphere or spheres earned in battle, which have different requirements depending on the ability.
License Board
Unlike FFX, in which you gain AP instead of XP, FFXII's LP, or License Points, are gained together with XP. LP can be used to purchase Licenses on the License Board, found here:
http://www.gamefaqs.com/console/ps2/file/459841/45740
Licenses are used not to gain abilities, but the ability to use abilities. For example, you can buy a Heavy Lance, but without the Spears 2 license, it cannot be equipped. It's the same with magick. A few licenses, called Augments, give instant, permanent bonuses to your characters, such as increased HP, decreased MP useage, increased block chance and the like.
So, there you have it. A crash course.