Prince of Wales heath vs Prince-of-Wales'-heath

Prince of Wales heath and Prince-of-Wales'-heath both are nouns.

Word	Noun	Adjective	Verb	Adverb
Prince of Wales heath	Yes	No	No	No
Prince-of-Wales'-heath	Yes	No	No	No

As nouns, Prince of Wales heath and Prince-of-Wales'-heath are synonyms defined as:

Prince of Wales heath and Prince-of-Wales'-heath: South African shrub grown for its profusion of white flowers

Other synonyms of Prince of Wales heath include Erica perspicua.

Prince of Wales heath (noun)	Prince-of-Wales'-heath (noun)
South African shrub grown for its profusion of white flowers	South African shrub grown for its profusion of white flowers