hard roll vs Vienna roll

hard roll and Vienna roll both are nouns.

Word	Noun	Adjective	Verb	Adverb
hard roll	Yes	No	No	No
Vienna roll	Yes	No	No	No

As nouns, hard roll and Vienna roll are synonyms defined as:

hard roll (noun)	Vienna roll (noun)
yeast-raised roll with a hard crust	yeast-raised roll with a hard crust