Guinea vs Republic of Guinea

Guinea and Republic of Guinea both are nouns.

Word	Noun	Adjective	Verb	Adverb
Guinea	Yes	No	No	No
Republic of Guinea	Yes	No	No	No

As nouns, Guinea and Republic of Guinea are synonyms defined as:

Guinea and Republic of Guinea: a republic in western Africa on the Atlantic; formerly a French colony; achieved independence from France in 1958

Other synonyms of Guinea include French Guinea.

Guinea (noun)	Republic of Guinea (noun)
a republic in western Africa on the Atlantic; formerly a French colony; achieved independence from France in 1958	a republic in western Africa on the Atlantic; formerly a French colony; achieved independence from France in 1958
(ethnic slur) offensive term for a person of Italian descent