"I was told..." The basic difference is that the time of the action is in the past, referring to a period of time that is now over. Remember: simple past and how it differs from present perfect? That still applies here.
To an extent. However, with 'being told', I am inclined to agree with SlickVic: "Though they're different tenses, I'd say there's little difference in meaning between the two phrases."
"I have been told..." can include that you have been told many times in the past, while the time you are speaking about remains open.
It can, but this is not an essential meaning associated with the present perfect.
Examples:
Yesterday, I was told that I look looked like my father.
I have also been told that I look like my mother. (intended time period left open, thus present perfect)
The first indicates that I was told once.
The second indicates that perhaps I have been told more than once.[
Once again, this is not necessarily the case. The key factor in using the past tense in the first example was the decision to place the telling in the past -
Yesterday. It's quite possible to say, "At the family reunion yesterday, I was told (by several people) that I looked like my father".
In British English, the present perfect is generally used often like the simple past.
It's perhaps more accurate to say that in BrE we tend to use the present perfect for very recent past events that may have some bearing on the present in situations when many speakers of AmE prefer the past simple -
I've just seen Mary (BrE);
I just saw Mary (AmE),
She hit me! Or: She's hit me!
Americans would generally stick to the simple past for that expression
In that particular example, I feel that many speakers of BrE would use a past simple if we were speaking immediately after the blow.