Differences between can, could and be able to

We can use "can" in present and "could" in past to express ability but "be able to" we can use in present, past and future.
Examples:
I can play the guitar. => I could play the guitar when I was a child.
I am able to play the guitar => I was able to play the guitar => I will able to play the guitar.

      Other differnece between is "can" is more usual  and   Can is probably more common in spoken English, simply because it’s shorter. But "be able to" is more stronger than "can" because I am able to do something

despite the consequences that may happen.

Example:

I can eat worms. (It can be only for a like only If I want or a possibility.)

I am able to eat worms. (It could be for example I have to do it for example If I should win a wager)