search vs rummage

search and rummage both are nouns.

Word	Noun	Adjective	Verb	Adverb
search	Yes	No	Yes	No
rummage	Yes	No	Yes	No

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

search: the activity of looking thoroughly in order to find something or someone
rummage: a thorough search for something (often causing disorder or confusion)

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

Other hyponyms of search include raid, frisk, strip-search, scan, go, rifle, comb, ransack.

search (noun)	rummage (noun)
the activity of looking thoroughly in order to find something or someone	a thorough search for something (often causing disorder or confusion)
boarding and inspecting a ship on the high seas	a jumble of things to be given away
an investigation seeking answers
the examination of alternative hypotheses
an operation that determines whether one or more of a set of items has a specified property

search (verb)	rummage (verb)
inquire into	search haphazardly
try to locate or discover, or try to establish the existence of
subject to a search
search or seek