driving iron vs one iron

driving iron and one iron both are nouns.

Word	Noun	Adjective	Verb	Adverb
driving iron	Yes	No	No	No
one iron	Yes	No	No	No

As nouns, driving iron and one iron are synonyms defined as:

driving iron and one iron: (golf) the long iron with the most nearly vertical face

driving iron (noun)	one iron (noun)
(golf) the long iron with the most nearly vertical face	(golf) the long iron with the most nearly vertical face