railing vs fife rail

railing and fife rail both are nouns.

Word	Noun	Adjective	Verb	Adverb
railing	Yes	No	No	No
fife rail	Yes	No	No	No

As nouns, fife rail is a hyponym of railing; that is, fife rail is a word with a more specific, narrower meaning than railing:

Other hyponyms of railing include bar, guardrail, safety rail, taffrail.

railing (noun)	fife rail (noun)
a barrier consisting of a horizontal bar and supports	the railing surrounding the mast of a sailing vessel
material for making rails or rails collectively