affinity vs relationship

affinity and relationship both are nouns.

Word	Noun	Adjective	Verb	Adverb
affinity	Yes	No	No	No
relationship	Yes	No	No	No

As nouns, relationship is a hypernym of affinity; that is, relationship is a word with a broader meaning than affinity:

affinity: (anthropology) kinship by marriage or adoption; not a blood relationship
relationship: (anthropology) relatedness or connection by blood or marriage or adoption

Other hypernyms of affinity include family relationship, kinship.

As nouns, relationship is a hypernym of affinity; that is, relationship is a word with a broader meaning than affinity:

affinity: (biology) state of relationship between organisms or groups of organisms resulting in resemblance in structure or structural parts
relationship: (anthropology) relatedness or connection by blood or marriage or adoption

Other hypernyms of affinity include family relationship, kinship.

affinity (noun)	relationship (noun)
inherent resemblance between persons or things	a relation between people; (`relationship' is often used where `relation' would serve, as in `the relationship between inflation and unemployment', but the preferred usage of `relationship' is for human relations or states of relatedness)
a natural attraction or feeling of kinship	(anthropology) relatedness or connection by blood or marriage or adoption
the force attracting atoms to each other and binding them together in a molecule	a state of connectedness between people (especially an emotional connection)
(immunology) the attraction between an antigen and an antibody	a state involving mutual dealings between people or parties or countries
(anthropology) kinship by marriage or adoption; not a blood relationship
(biology) state of relationship between organisms or groups of organisms resulting in resemblance in structure or structural parts
a close connection marked by community of interests or similarity in nature or character