St. Peter's wreath vs Saint Peter's wreath

St. Peter's wreath and Saint Peter's wreath both are nouns.

Word	Noun	Adjective	Verb	Adverb
St. Peter's wreath	Yes	No	No	No
Saint Peter's wreath	Yes	No	No	No

As nouns, St. Peter's wreath and Saint Peter's wreath are synonyms defined as:

St. Peter's wreath and Saint Peter's wreath: shrub having copious small white flowers in spring

Other synonyms of St. Peter's wreath include bridal-wreath, bridal wreath, Spiraea prunifolia.

St. Peter's wreath (noun)	Saint Peter's wreath (noun)
shrub having copious small white flowers in spring	shrub having copious small white flowers in spring