able

@ One man is able to destroy this city. (X)

@ One man is capable to destroy this city. (V)

Note :

If someone is ABLE TO DO SOMETHING, they can do it and it is unusual or surprising if they do it. Examples :
- The doctor said that you would be able to get up after a few days.
- Will you be able to come to my house tomorrow?

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. Examples :
- I am sure he is quite capable to get there on time, but he can't be given another task.
- The power supply is capable of generating enough electricity for this city.