Generally, in English, when you ‘hear about’ something you find out the details or the situation (what is/was/will be happening). When you hear of something or someone you learn that it or the person exists.
‘Have you heard about Sarah and Ben?’
‘I knew they got together into a relationship. However, tell me all about it.’
‘Have you heard of the film ‘Titanic’?’
‘No, I’ve never heard of it.’
‘Have you heard of Vladimir Putin?’
‘Yes, he is the Russian leader’.
Jim: ‘I come from a small city called Oxford. It’s
located in England. Have you ever heard of it?’
Pete: ‘Yep. I have heard of it ( = recognise the name). And I have heard about it too as it has a famous university there. I have heard that many students around the world aspire to study in Oxford!’
Hoping that helps. Remember we do personalised English classes on Skype. Just follow the link for more details!