CENTRE OR CENTER?
Just like the Spanish in Spain is different to the Spanish in South America, there are also some differences between British English and American English.
The word "centre or center" is a good example of this. In the UK we use the word "centre" like for example: business centre or shopping centre. The American use a different version of the word and write it: "center". So they would say "shopping center" or "mall".
So, the answer to the question about which one is correct is: they are both right, it just depends on where you are located.
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.