storage vs stockpiling

storage and stockpiling both are nouns.

Word	Noun	Adjective	Verb	Adverb
storage	Yes	No	No	No
stockpiling	Yes	No	No	No

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

storage (noun)	stockpiling (noun)
the commercial enterprise of storing goods and materials	accumulating and storing a reserve supply
the act of storing something
depositing in a warehouse
a depository for goods
an electronic memory device
(computer science) the process of storing information in a computer memory or on a magnetic tape or disk