continue vs span

continue is not a noun while span is a noun.

Word	Noun	Adjective	Verb	Adverb
continue	No	No	Yes	No
span	Yes	No	Yes	No

As verbs, span is a hyponym of continue; that is, span is a word with a more specific, narrower meaning than continue:

Other hyponyms of continue include cross, sweep, traverse, sweep, overlap, overspread, spread, ridge, constellate, dot, stud.

continue (noun)	span (noun)
	the act of sitting or standing astride
	a structure that allows people or vehicles to cross an obstacle such as a river or canal or railway etc.
	the distance or interval between two points
	a unit of length based on the width of the expanded human hand (usually taken as 9 inches)
	two items of the same kind
	the complete duration of something

continue (verb)	span (verb)
exist over a prolonged period of time	to cover or extend over an area or time period
continue talking
move ahead; travel onward in time or space
allow to remain in a place or position or maintain a property or feature
keep or maintain in unaltered condition; cause to remain or last
continue a certain state, condition, or activity
span an interval of distance, space or time
continue in a place, position, or situation
continue after an interruption
do something repeatedly and showing no intention to stop