Lord's Supper vs Seder

Lord's Supper and Seder both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lord's Supper	Yes	No	No	No
Seder	Yes	No	No	No

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

Lord's Supper: the traditional Passover supper of Jesus with his disciples on the eve of his crucifixion
Seder: (Judaism) the ceremonial dinner on the first night (or both nights) of Passover

Other hypernyms of Lord's Supper include Passover supper.

Lord's Supper (noun)	Seder (noun)
a Christian sacrament commemorating the Last Supper by consecrating bread and wine	(Judaism) the ceremonial dinner on the first night (or both nights) of Passover
the traditional Passover supper of Jesus with his disciples on the eve of his crucifixion