grappling hook vs grappling iron

grappling hook and grappling iron both are nouns.

Word	Noun	Adjective	Verb	Adverb
grappling hook	Yes	No	No	No
grappling iron	Yes	No	No	No

As nouns, grappling hook and grappling iron are synonyms defined as:

grappling hook and grappling iron: a tool consisting of several hooks for grasping and holding; often thrown with a rope

Other synonyms of grappling hook include grapnel, grapple, grappler.

grappling hook (noun)	grappling iron (noun)
a tool consisting of several hooks for grasping and holding; often thrown with a rope	a tool consisting of several hooks for grasping and holding; often thrown with a rope