SORRY, SOME MISTAKES ABOVE
In fact, we Vietnamese never use these pronouns in speaking! (but you can see many of them in Vietnamese films because Vietnamese films does not reflects the reality)
"anh ta" or "cô ta" is less formal than "anh ấy" or "cô ấy". But all of them are used in writing or formal occasions only.
If you want to use "he", "she" in Vietnamese, just add “đấy" (that +N) right after the noun or just repeat the name or just use the noun only.
1. PUTTING "
e.g. A: Lisa đẹp thật.
B: Con đấy là ai? (Who's that girl? = Who is she). CON means GIRL informally.
2. REPEAT THE NAME
e.g. A: David Beckham đá bóng hay thật.
B: David Beckham là ai? (Who's David Beckham? = Who is he?)
3. USING THE NOUN ONLY
e.g. Johnson là bác sĩ giỏi. Ông đã giúp nhiều người (Ông = old man but here the sentence is: He/The old man helps many people)