sheet pile vs piling

sheet pile and piling both are nouns.

Word	Noun	Adjective	Verb	Adverb
sheet pile	Yes	No	No	No
piling	Yes	No	No	No

As nouns, piling is a hypernym of sheet pile; that is, piling is a word with a broader meaning than sheet pile:

sheet pile: a pile in a row of piles driven side by side to retain earth or prevent seepage
piling: a column of wood or steel or concrete that is driven into the ground to provide support for a structure

Other hypernyms of sheet pile include pile, spile, stilt.

sheet pile (noun)	piling (noun)
a pile in a row of piles driven side by side to retain earth or prevent seepage	a column of wood or steel or concrete that is driven into the ground to provide support for a structure