bidding vs declaration

bidding and declaration both are nouns.

Word	Noun	Adjective	Verb	Adverb
bidding	Yes	No	No	No
declaration	Yes	No	No	No

As nouns, declaration is a hyponym of bidding; that is, declaration is a word with a more specific, narrower meaning than bidding:

bidding: (bridge) the number of tricks a bridge player is willing to contract to make
declaration: (contract bridge) the highest bid becomes the contract setting the number of tricks that the bidder must make

Other hyponyms of bidding include contract, takeout, overbid, overcall, pre-empt, preempt, preemptive bid.

bidding (noun)	declaration (noun)
a request to be present	a statement that is emphatic and explicit (spoken or written)
(bridge) the number of tricks a bridge player is willing to contract to make	a formal expression by a meeting; agreed to by a vote
an authoritative direction or instruction to do something	(law) unsworn statement that can be admitted in evidence in a legal transaction
	a formal public statement
	(contract bridge) the highest bid becomes the contract setting the number of tricks that the bidder must make
	a statement of taxable goods or of dutiable properties