11 November vs St Martin's Day

11 November and St Martin's Day both are nouns.

Word	Noun	Adjective	Verb	Adverb
11 November	Yes	No	No	No
St Martin's Day	Yes	No	No	No

As nouns, 11 November and St Martin's Day are synonyms defined as:

11 November and St Martin's Day: the feast of Saint Martin; a quarter day in Scotland

Other synonyms of 11 November include Martinmas.

11 November (noun)	St Martin's Day (noun)
the feast of Saint Martin; a quarter day in Scotland	the feast of Saint Martin; a quarter day in Scotland