The Common Core State Standards for Mathematics can be found here:
http://www.corestandards.org/Math/
Besides the mathematical standards, see also about the standards, what parents should know, and whatever other parts of the site that may be of interest. From the about section's FAQ:
As to your [edited] post, you write:
So is the common core really something normalized for everybody, yet, there is a difference in what is being learned?
The Common Core is normalized in the sense that the standards are freely available; they are in the first link above, and they can be searched through quite easily using the site. For example, here is a search through the Math Standards for the word 'matrix' to show where and how it appears.
It seems to me that the issue you are describing is around curriculum; note that in the first excerpt above, it says (emphasis in original) that, "Education standards, like Common Core are not a curriculum." Curricular concerns -- picking one, adhering to one, supplementing one, etc -- are major issues facing mathematics teachers.
In just the past couple weeks, Matt Larson (current NCTM President) put out a post on curricular coherence in the age of open educational resources; see also the response from Dan Meyer (link) who has a pointer to another post by (former student of mine! -- though I take no credit -- and occasional contributor to this site, MESE) Tyler Auer (link).
So, concerns like yours are prominent right now among math educators -- including but not limited to math teachers and curriculum writers. Succinctly, to respond to another excerpt from your post:
Why is there some material that does not get covered, yet it is very important to learn, or much yet be exposed to?
One response is, there is more "important to learn" material than could possibly be covered. But another response is, if the Common Core Standards for Mathematics were properly addressed within a curriculum (but whose responsibility is this?) then you would see, for example, matrices and conic sections. The discrepancy in how to meet the Standards' learning goals is an important area of contemporary consideration.
Finally, a digital resource: For a nice online "Common Core Curriculum" to address both the ELA and Mathematics Standards, you might check out the materials freely available at $\text{engage}^\text{ny}$ (link).