endocarp vs seed vessel

endocarp and seed vessel both are nouns.

Word	Noun	Adjective	Verb	Adverb
endocarp	Yes	No	No	No
seed vessel	Yes	No	No	No

As nouns, seed vessel is a hypernym of endocarp; that is, seed vessel is a word with a broader meaning than endocarp:

endocarp: the hard inner (usually woody) layer of the pericarp of some fruits (as peaches or plums or cherries or olives) that contains the seed
seed vessel: the ripened and variously modified walls of a plant ovary

Other hypernyms of endocarp include pericarp.

endocarp (noun)	seed vessel (noun)
the hard inner (usually woody) layer of the pericarp of some fruits (as peaches or plums or cherries or olives) that contains the seed	the ripened and variously modified walls of a plant ovary