I will be the first to agree that naming in neuroscience could be better.
As I understand it, the sheet of the cortex is composed of what is generally recognized as six layers.
The outer layer (one furthest from the center of the brain) is called layer one
The bottom is generally called layer six. These are not hard and fast divisions as the whole concept of what makes up a layer is pretty loose at this time. There are some that consider the thalamus as the 7th layer.
This same sheet of the cortex has subtle variations that are discernable with different methods. Two of the oldest are inspection with low power magnification, or by noting what defects occur if some area is damaged - say by a war wound.
These older techniques have settled on the map offered by Brodmann:
these can be called maps, areas, or regions - all mean the same thing.
One of the newer techniques is to look with various 3D imaging methods and follow the connecting tracts - what is hooked to what.
This method has roughly doubled the number of identified maps/areas/regions.
The tool that has come out of this effort is the connectogram, see this list of maps at the bottom of this link:
It has been observed that in these map-to-map connections there are definite pathways. In these streams, there is a general scheme of progressing from the senses to the association region. Each of the sensory modalities seems to have this processing stream and this progression from senses to the association region is generally referred to as a hierarchy. There are similar streams in other places in the brain but that is more complicated than I want to tackle in an introductory post.
I want to add that these graphs that show a general stream make it look simple. This can be deceiving as in reality, the brain is very complex with a bewildering collection of skips and side connections in these streams. This paper should give a more realistic view of what a neuro-scientist is up against - see figure 1:
But wait - there’s more!
The progression of processing the main sensory streams seems to be split into two major paths - one is called the WHAT stream, and one is called the WHERE stream.
Do you want to dig deeper?
Here is some associated reading that should show these streams in action and give you a flavor for what is going on. You can skip these without guilt as they are more in-depth than most newbies are ready to digest.