Question:Have you ever gone to see a doctor
Superman:No, I haven't, I don't get sick.
Q: Did you see the(your) doctor?
A1:Yes, I did
A2:No, I haven't seen him yet. I'm still in his waiting room and reading a magazine.
Here I have examplified what I know about the difference between these two tenses, but what I know is not always necessarily what it should be.(since I'm not a native-speaker)