Guyana vs British Guiana

Guyana and British Guiana both are nouns.

Word	Noun	Adjective	Verb	Adverb
Guyana	Yes	No	No	No
British Guiana	Yes	No	No	No

As nouns, Guyana and British Guiana are synonyms defined as:

Guyana and British Guiana: a republic in northeastern South America; formerly part of the British Empire, but it achieved independence from the United Kingdom in 1966

Other synonyms of Guyana include Co-operative Republic of Guyana.

Guyana (noun)	British Guiana (noun)
a republic in northeastern South America; formerly part of the British Empire, but it achieved independence from the United Kingdom in 1966	a republic in northeastern South America; formerly part of the British Empire, but it achieved independence from the United Kingdom in 1966