ownership vs holding

ownership and holding both are nouns.

Word	Noun	Adjective	Verb	Adverb
ownership	Yes	No	No	No
holding	Yes	No	No	No

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

ownership (noun)	holding (noun)
the act of having and controlling property	the act of retaining something
the relation of an owner to the thing possessed; possession with the right to transfer possession to others	something owned; any tangible or intangible possession that is owned by someone
the state or fact of being an owner