All the answers below are true from other responders. I would tend to say that a specific act is selfish. "That was a very selfish thing to do," though I can use it to describe a person in general. I would tend to say that a person is by nature, self-centered. "He is a very self-centered person." Taking it a step further. "Donald Trump goes beyond being self-centered, he is a pure narcissist." Hope that helps!

In practice, probably not a great difference. Perhaps, selffish means "me first", before others Whereas a truely self-centred people might not even think about sharing. . But pretty similar.

I'd agree with Gerry Weitz. "Self-centred" refers to a person's nature. It's more long-term, and suggests that it is intrinsic to that person's character. "Selfish" refers more to a person's actions. For example "Don't be selfish!" or "You just did a really selfish thing". Where "selfish" does refer to a person, it may be shorter term. For example, you could perhaps persuade someone not to be selfish about something, but you are unlikely to be able to change someone who is fundamentally self-centred.

The difference between "selfish" and "self-centered" actually lies in the intensity or the person who is in front of you. I mean, "selfish" is kind of a 'cheap' word which you can easily use in front of your friends. Well, if you are in a reputed or good place and among elders , I would suggest you to use the word "self-centered" because that sounds good and in a way, it makes you look a man with etiquettes. Nonetheless, both the words have more or less the same meaning.

True the differences are subtle however, being selfish has an emphasis on a lack of consideration for those around them. They will do anything and everything to gain respect, money, power, or whatever, even if it causes harm to their loved ones. It's more negative in a sense. Whereas self-centered people are often just pre-occupied with themselves.