There are four levels defined within Buddhism. The first level is called Stream-enterer, where a person has tasted full enlightenment, but cannot hold it. On that level though, they are partially purified. If a person reaches the first level of enlightenment, they will never break the five precepts, it is absolutely guaranteed they just won't do it, it's not within their nature. They are purified enough that they will never break them. It is taught that a person who has reached the first level is guaranteed that full enlightenment will come within seven lifetimes. So that even on the first level, it's partial, it's not full, but they have tasted it, they know it, and they are guaranteed within supposedly seven lifetimes that they will achieve full enlightenment.
Then the second level, which is called Once-returner, a person will be reborn as a human one more time before they're enlightened. In that stage they have eradicated more of their anger and fear. The first level doesn't eradicate it, but reduces it, so that they'll never break the five precepts. The second level basically gets rid of almost all aversion fear and so on, but not all of it, there are still subtle amounts.
The third level called, Non-returner, is that the person will never get reborn as a human again. They get reborn once more in a special type of heaven realm and they get fully enlightened up there. On the non-returner level, they have no more sense desires and aversions, they have absolutely none. But they still have some ego, they still have some conceit, some worry, restlessness in the mind, and that's blocking them from the full enlightenment.
Then there's the full enlightenment called Arahant, or for a Buddha, it's called being a Buddha. Those are the four stages.
I might also add that it is taught not everyone goes through the stages A, B, C, D. Some people will just automatically get fully enlightened, they don't go through any of the other stages.
However, someone who's not enlightened could still be very wise. With the Buddha, because Buddhism teaches past lives, in five hundred of his past lives he was called a Bodhisattva. That's a term used to signify a person who is destined to become a Buddha, but is not one yet, they're working towards it.
A Bodhisattva can never become partly enlightened, because if they become partly enlightened then they can't be a Buddha. A Buddha discovers the enlightenment for himself, so a person who is already partly enlightened has already been taught by someone else and then achieved partial enlightenment. So a Bodhisattva is going to be somebody who is very wise, but not even partly enlightened. So if this teaching is true, there might be people around today who might be Bodhisattvas.