sheet piling vs piling

sheet piling and piling both are nouns.

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

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

sheet piling: 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 piling include pile, spile, stilt.

sheet piling (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