split-rail fence vs rail fence

split-rail fence and rail fence both are nouns.

Word	Noun	Adjective	Verb	Adverb
split-rail fence	Yes	No	No	No
rail fence	Yes	No	No	No

As nouns, split-rail fence and rail fence are synonyms defined as:

split-rail fence and rail fence: a fence (usually made of split logs laid across each other at an angle)

split-rail fence (noun)	rail fence (noun)
a fence (usually made of split logs laid across each other at an angle)	a fence (usually made of split logs laid across each other at an angle)