Vienna roll vs hard roll

Vienna roll and hard roll both are nouns.

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

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

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