【Couple】 , 【pair】 , 【brace】 , 【yoke】 are comparable when meaning two things of the same kind.

【Couple】 applies to two things of the same sort, regarded as in some way associated, but not necessarily (except in the case of a married or mated 【pair】 ) matched or belonging together; it frequently means no more than two.

【Pair】 applies to two things that belong or are used together, frequently so that one is useless or defective without the other; it also applies to a single object (as trousers, spectacles, scissors, or tongs) composed of two corresponding or complementary parts.

【Brace】 applies especially to a 【couple】 of certain animals or occasionally, to a 【couple】 of inanimate objects or rarely and usually with contemptuous connotations to persons.

【Yoke】 applies to two animals linked together. It is used of persons only in contempt.