open-face sandwich vs open sandwich

open-face sandwich and open sandwich both are nouns.

Word	Noun	Adjective	Verb	Adverb
open-face sandwich	Yes	No	No	No
open sandwich	Yes	No	No	No

As nouns, open-face sandwich and open sandwich are synonyms defined as:

open-face sandwich and open sandwich: sandwich without a covering slice of bread

open-face sandwich (noun)	open sandwich (noun)
sandwich without a covering slice of bread	sandwich without a covering slice of bread