Able = Having the power , means or opportunity to do something.
- Will you be able to come?
- They need to be able to irrigate without relying solely on rain water.
- He has informed his ability to attend the meeting.
Capable = Having the ability or fitness or quality necessary to do or achieve a SPECIFIED thing.
- Show your teacher what you are capable of.
- He is quite capable of taking care of himself.
- Only the democratic party is capable of running the administration.
- Automation gives us the capability to do certain jobs quickly and well.
- A very capable doctor/nurse/teacher.
- I think your plan is capable being improved.
- We have to further improve our nuclear capability considering the local situations.