cachet vs seal

cachet and seal both are nouns.

Word	Noun	Adjective	Verb	Adverb
cachet	Yes	No	No	No
seal	Yes	No	Yes	No

As nouns, seal is a hypernym of cachet; that is, seal is a word with a broader meaning than cachet:

cachet: a seal on a letter
seal: a device incised to make an impression; used to secure a closing or to authenticate documents

Other hypernyms of cachet include stamp.

As nouns, cachet and seal are synonyms defined as:

Other synonyms of cachet include seal of approval.

cachet (noun)	seal (noun)
a seal on a letter	any of numerous marine mammals that come on shore to breed; chiefly of cold regions
an indication of approved or superior status	a device incised to make an impression; used to secure a closing or to authenticate documents
a warrant formerly issued by a French king who could warrant imprisonment or death in a signed letter under his seal	fastener consisting of a resinous composition that is plastic when warm; used for sealing documents and parcels and letters
	fastener that provides a tight and perfect closure
	a finishing coat applied to exclude moisture
	an indication of approved or superior status
	a stamp affixed to a document (as to attest to its authenticity or to seal it)
	the pelt or fur (especially the underfur) of a seal

cachet (verb)	seal (verb)
	decide irrevocably
	hunt seals
	close with or as if with a seal
	affix a seal to
	make tight; secure against leakage
	cover with varnish