sash vs waistband

sash and waistband both are nouns.

Word	Noun	Adjective	Verb	Adverb
sash	Yes	No	No	No
waistband	Yes	No	No	No

As nouns, sash and waistband are synonyms defined as:

sash and waistband: a band of material around the waist that strengthens a skirt or trousers

Other synonyms of sash include cincture, girdle, waistcloth.

sash (noun)	waistband (noun)
a framework that holds the panes of a window in the window frame	a band of material around the waist that strengthens a skirt or trousers
a band of material around the waist that strengthens a skirt or trousers