section vs subdivision

section and subdivision both are nouns.

Word	Noun	Adjective	Verb	Adverb
section	Yes	No	Yes	No
subdivision	Yes	No	No	No

As nouns, subdivision is a hyponym of section; that is, subdivision is a word with a more specific, narrower meaning than section:

section: one of several parts or pieces that fit with others to constitute a whole object
subdivision: a section of a section; a part of a part; i.e., a part of something already divided

Other hyponyms of section include bend, curve, dado, leaf, length, straight, straightaway, subsection.

As nouns, section and subdivision are synonyms defined as:

section and subdivision: a self-contained part of a larger composition (written or musical)

section (noun)	subdivision (noun)
the cutting of or into body tissues or organs (especially by a surgeon as part of an operation)	the act of subdividing; division of something previously divided
one of several parts or pieces that fit with others to constitute a whole object	a section of a section; a part of a part; i.e., a part of something already divided
one of the portions into which something is regarded as divided and which together constitute a whole	a self-contained part of a larger composition (written or musical)
a self-contained part of a larger composition (written or musical)	a division of some larger or more complex organization
a segment of a citrus fruit	an area composed of subdivided lots
a small army unit usually having a special function
a division of an orchestra containing all instruments of the same class
a small team of policemen working as part of a police platoon
a specialized division of a large organization
a small class of students who are part of a larger course but are taught separately
(geometry) the area created by a plane cutting through a solid
a distinct region or subdivision of a territorial or political area or community or group of people
a very thin slice (of tissue or mineral or other substance) for examination under a microscope
a land unit equal to 1 square mile

section (verb)	subdivision (verb)
divide into segments