subdivision vs segmentation

subdivision and segmentation both are nouns.

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

As nouns, segmentation is a hypernym of subdivision; that is, segmentation is a word with a broader meaning than subdivision:

subdivision: the act of subdividing; division of something previously divided
segmentation: the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart

Other hypernyms of subdivision include division, partition, partitioning, sectionalisation, sectionalization.

subdivision (noun)	segmentation (noun)
the act of subdividing; division of something previously divided	the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart
a section of a section; a part of a part; i.e., a part of something already divided	(embryology) the repeated division of a fertilised ovum
a self-contained part of a larger composition (written or musical)
a division of some larger or more complex organization
an area composed of subdivided lots