In our language, the difference between the two sentences is very vague.
What is the difference between "I was there" and "I have been there"?
The question is broad and depending on the context, the meaning of those sentences drastically change. Since the question is broad, I'll answer that way.
Both the sentences broadly mean the same - you (at some point in time) were present at that place. However, a subtle difference is...
I was there - merely talks about the past event that you were present at that place.
I have been there - talks about the past event of you being there but also emphasize that that event has something to do in the present talk/scenario. The current scenario/talk could be the result of you being there.
I remember it like this: One is referring to a specific date/time, the other is generalized: you are just letting the speaker know you were there at some point in the past, but the date/time is irrelevant.
- I was there at the store. (e.g., Last Friday night on New Year's Eve)
- I have been to the store. (e.g. I've been to the store before)
- I saw Green Day play there. (e.g. in 2004 during the American Idiot tour)
- I have seen Green Day play there (e.g. I'm just informing the listener I've seen Green Day play there at some point before. We're not concerned with when.)
- I phoned Jim. (e.g. 2 minutes ago)
- I have phoned Jim (Just informing you that at some point up to now Jim has been called.
Simple past (was/saw) - Used to refer a specific event/date in the past that you did the act. The event (WHEN it happened) is the the important part of the information.
Present Perfect Simple (have been/have seen) - Used to let the listener know that you did a certain act at some point in the past. Generalized. The concern is the present, and what you did leading up to present.