line of questioning vs argument

line of questioning and argument both are nouns.

Word	Noun	Adjective	Verb	Adverb
line of questioning	Yes	No	No	No
argument	Yes	No	No	No

As nouns, argument is a hypernym of line of questioning; that is, argument is a word with a broader meaning than line of questioning:

line of questioning: an ordering of questions so as to develop a particular argument
argument: a course of reasoning aimed at demonstrating a truth or falsehood; the methodical process of logical reasoning

Other hypernyms of line of questioning include argumentation, line, line of reasoning, logical argument.

line of questioning (noun)	argument (noun)
an ordering of questions so as to develop a particular argument	a variable in a logical or mathematical expression whose value determines the dependent variable; if f(x)=y, x is the independent variable
	a course of reasoning aimed at demonstrating a truth or falsehood; the methodical process of logical reasoning
	a discussion in which reasons are advanced for and against some proposition or proposal
	a summary of the subject or plot of a literary work or play or movie
	a fact or assertion offered as evidence that something is true
	a contentious speech act; a dispute where there is strong disagreement
	(computer science) a reference or value that is passed to a function, procedure, subroutine, command, or program