What are the principal distinguishing characteristics of the bones of the various regions of the vertebral column?

I don't know if you're a medical student, but I certainly am not, so I'll try to answer your question in layman's terms!   The vertebral column is comprised of 33 bones, divided into five main regions:  cervical, thoracic, lumbar, and pelvic.  In the following paragraphs, I will give the most distinguishing characteristics of the bones in each region and discuss what functions they serve to the body.

Cervical:   There are seven bones in this section.  We will call them C1-C7 for identification purposes.  C1, the Atlas, is the topmost vertebrae connecting the skull to the rest of the spine and is the pivot for nodding the head.  It has no body because it's fused to C2.  C2, the axis, is the pivot upon which the head turns side to side.  It's the first bone to have a bony protruberence, and it sits on top of and slightly overlapping C3.  C3-C6 have smaller bodies and are broader from side to side than front to back, and each one slightly overlaps the one beneath it.   C7, or vertebra prominens, is different because it has a very prominent bony protruberence. "The cervical spine is comparatively mobile, and some component of this movement is due to flexion and extension of the vertebral column itself."

Thoracic:  There are twelve bones in this section.  We will call them T1-T12.  These bones are basically all the same:  heart-shaped, thick, and broad, getting progressively larger in size as they go down the spine, and overlapping each other like tiles on a roof.  What makes them unique is that they all have special plates, called "costal facets" on either side of them for attachment of the ribs.  Because the ribs are not permanently fused to the vertebra, but joined by ligaments and connective tissue,  the chest can lift outwards and expand when we breathe. 

Lumbar:  There are five bones in this section.  Their names are L1-L5.  (Some people have six bones in this section.)  By far the largest and strongest of the bones in the vertebral column, they carry the weight of the whole body, are the source of most body motion, and enable us to stand erect.  Each lumbar vertebra is wider from side to side than front to back, and slightly thicker in front than in back. 

Pelvic:  The pelvic region is composed of the sacral bones (five fused bones) and the coccygeal bones (3-5 fused bones), commonly called the "tailbone."  This is the region of the body where the hips attach, so these bones are important to the rigidity, flexibility, stability, and function of the skeleton. 

It is important to note that the curves of the vertebral column are important as well  They enable us to stand erect, balance, walk, and move in the many different ways we do. 

I used several different sites on Wikipedia to gather my information. ( In addition to the reference listed below, I looked up articles on cervical, thoracic, and lumbar.)