people who are more or less proficient in both languages but will not necessarily pass for a native speaker in both languages

a person nos strong in either/any language

a person who is a native speaker in one and is capable of understanding but not speaking another language

a person who is more proficient in one of the two languages

a person who passes in any situation in both languages for a native speaker

a person who has two separate linguistic systems and can handle each of them easily, usually because each parent has and speaks in a different mother tongue to the child