as if 가정법 문장 구분이 궁금해요

as if가 가정법으로 쓰이는 경우와 사실을 말하는 경우를 구분하고 싶어요.
“She acts as if she were a star”와 “She acts as if she is a star”는 시제 차이로 이해했어요.
그런데 “She acted as if she had been a star”와 “She acted as if she were a star”도 둘 다 가정법인가요?
뒤 문장이 “She talked as if she were a nurse”와 같은 구조라서 헷갈립니다.