noun
Congo person; Congolese
Refers to a person from the Republic of the Congo or the Democratic Republic of the Congo. Context usually clarifies which country is meant.
彼はコンゴ人で、キンシャサ出身だ。
He is Congolese, from Kinshasa.
noun
Kongo person; Bakongo person
Refers specifically to a member of the Kongo ethnic group, not necessarily a citizen of a Congo country.
コンゴ人はバントゥー系の民族だ。
The Kongo people are a Bantu ethnic group.