line of descent vs side

line of descent and side both are nouns.

Word	Noun	Adjective	Verb	Adverb
line of descent	Yes	No	No	No
side	Yes	Yes	Yes	No

As nouns, side is a hyponym of line of descent; that is, side is a word with a more specific, narrower meaning than line of descent:

Other hyponyms of line of descent include family, family line, folk, kinfolk, kinsfolk, phratry, sept, breed line.

line of descent (noun)	side (noun)
the hereditary derivation of an individual	an extended outer surface of an object
the kinship relation between an individual and the individual's progenitors	either the left or right half of a body
	an aspect of something (as contrasted with some other implied aspect)
	an opinion that is held in opposition to another in an argument or dispute
	(sports) the spin given to a ball by striking it on one side or releasing it with a sharp twist
	a lengthwise dressed half of an animal's carcass used for food
	one of two or more contesting groups
	a family line of descent
	a surface forming part of the outside of an object
	a line segment forming part of the perimeter of a plane figure
	a place within a region identified relative to a center or reference location
	an elevated geological formation

line of descent (adjective)	side (adjective)
	located on a side

line of descent (verb)	side (verb)
	take sides for or against