be able to do : ~할 능력 있다. 가능성이 있다.
be capable of ~ing : ~할 능력이 있다. ~을 감당해 내다
One man is able to destroy the whole world. (X)
One man is capable of destroying the whole world.(0)
▢ be able to
If someone is able to do something, they can do it and it is not unusual or surprising if they do it.
ex) Three weeks after the accident, she was able to walk.
ex) Will you be able to play on Saturday?
ex) You will be able to have a good time with your parents.
▢ be capable of
If someone is capable of (doing) something, they do not usually do it, but it is possible for them to do it if they want to.
ex) The power station is capable of generating enough electricity for the whole region.
ex) She's capable of murder when she loses her temper