It's a lot broader than that. The sphere system is completely orthogonal to the existing spells, you can use it in addition to the normal spells or as a replacement.
There's 20 spheres in the base book. (Some examples are Conjuration, Destruction, Illusion, Weather, Time, and Mind.) Each sphere gives you access to 1-3 effects, some of which are at-will, some of which cost spell points. (Full casters have spell points equal to their level + Casting mod.) Each sphere also has a list of talents, which generally give alternate effects to the base power or enhance the range and potency of the effect. Full casters generally gain between 1-2 talents each level, which can be spent to either gain a talent or a new sphere.
Crucially, the base effects and talents scale with level; you don't need to spend all your talent points in 1-2 spheres to keep them relevant. A caster who chooses to put all their talents into one sphere will have access to a much greater breadth and depth of options. Just putting one point into Weather, for example, will let a caster summon up rain, a solid amount of wind, and raise or drop the temperature by 10s of degrees. Putting all your points into Weather pretty much turns you into Storm from X-Men.
There's also sections on new classes that utilize and build on the Sphere system, how to adapt the existing PHB classes into the Sphere system, Advanced Talents that are level-gated to allow for more potent effects, and a large section of boons and drawbacks that allow the DM or player to build their own casting traditions, if they want to have a more focused set of casting abilities that fit their setting.
www.kickstarter.com
