grappling iron vs grapnel

grappling iron and grapnel both are nouns.

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

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

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

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

grappling iron (noun)	grapnel (noun)
a tool consisting of several hooks for grasping and holding; often thrown with a rope	a light anchor for small boats
	a tool consisting of several hooks for grasping and holding; often thrown with a rope