continuance vs span

continuance and span both are nouns.

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

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

Other hyponyms of continuance include clocking, longueur, residence time, stint, stretch, time scale, note value, time value, value, rule.

continuance (noun)	span (noun)
the act of continuing an activity without interruption	the act of sitting or standing astride
the property of enduring or continuing in time	a structure that allows people or vehicles to cross an obstacle such as a river or canal or railway etc.
the period of time during which something continues	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

continuance (verb)	span (verb)
	to cover or extend over an area or time period