increase vs upsurge

increase and upsurge both are nouns.

Word	Noun	Adjective	Verb	Adverb
increase	Yes	No	Yes	No
upsurge	Yes	No	No	No

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

increase (noun)	upsurge (noun)
the act of increasing something	a sudden or abrupt strong increase
the amount by which something increases	a sudden forceful flow
a change resulting in an increase
a process of becoming larger or longer or more numerous or more important
a quantity that is added

increase (verb)	upsurge (verb)
become bigger or greater in amount
make bigger or more