z-fold vs concertina fold

z-fold and concertina fold both are nouns.

Word	Noun	Adjective	Verb	Adverb
z-fold	Yes	No	No	No
concertina fold	Yes	No	No	No

As nouns, z-fold and concertina fold are synonyms defined as:

z-fold and concertina fold: a continuous parallel folding in an accordion-like fashion, that is with folds alternatively made to the front and back in zig-zag folds.

Other synonyms of z-fold include accordion fold, zig-zag fold.

z-fold (noun)	concertina fold (noun)
a continuous parallel folding in an accordion-like fashion, that is with folds alternatively made to the front and back in zig-zag folds.	a continuous parallel folding in an accordion-like fashion, that is with folds alternatively made to the front and back in zig-zag folds.