Remembrance Sunday vs Poppy Day

Remembrance Sunday and Poppy Day both are nouns.

Word	Noun	Adjective	Verb	Adverb
Remembrance Sunday	Yes	No	No	No
Poppy Day	Yes	No	No	No

As nouns, Remembrance Sunday and Poppy Day are synonyms defined as:

Remembrance Sunday and Poppy Day: the Sunday nearest to November 11 when those who died in World War I and World War II are commemorated

Other synonyms of Remembrance Sunday include Remembrance Day.

Remembrance Sunday (noun)	Poppy Day (noun)
the Sunday nearest to November 11 when those who died in World War I and World War II are commemorated	the Sunday nearest to November 11 when those who died in World War I and World War II are commemorated