funday vs Lord's Day

funday and Lord's Day both are nouns.

Word	Noun	Adjective	Verb	Adverb
funday	Yes	No	No	No
Lord's Day	Yes	No	No	No

As nouns, Lord's Day is a hypernym of funday; that is, Lord's Day is a word with a broader meaning than funday:

funday: Sunday as a day for relaxing and having fun
Lord's Day: first day of the week; observed as a day of rest and worship by most Christians

Other hypernyms of funday include Dominicus, Sun, Sunday.

funday (noun)	Lord's Day (noun)
Sunday as a day for relaxing and having fun	first day of the week; observed as a day of rest and worship by most Christians