Select means to carefully choose; it also means to use a mouse or keystrokes to mark something on a computer screen.
In both the cases, the number of things chosen or marked does not influence which verb is used.
One main difference is the preposition that usually follows each of these words. Typically, you see able to, but capable of.
Other than that, pick a dictionary, look the two words up. I'm citing Collins:
able (adj.)
1. having the necessary power, resources, skill, time, opportunity, etc, to do something ⇒ able to swim
2. capable; competent; talented ⇒ an able teacher
3. (law) qualified, competent, or authorized to do some specific act
capable (adj.)
1. having ability, esp in many different fields; competent
2. able or having the skill (to do something) ⇒ she is capable of hard work
3. having the temperament or inclination (to do something) ⇒ he seemed capable of murder
You can see a lot of overlap, particularly with definitions #1 & #2 for capable, and definition #2 for able. Both words mean competent; plus, able means capable, and capable means able. This means there will be several contexts where either word could be used:
Sammy is an able electrician; I would recommend him.
Tammie is a capable electrician; I would recommend her.
Evan has shown he is able to reach the green from the tee box.
Kevin has shown he is capable of reaching the green from the tee box.
However, the definitions also show instances where one word couldn't be exchanged for the other:
I have to catch a flight; I won't be able to hold the meeting this afternoon.
⇒ This is able Definition #1; capable is not appropriate here.
Because I didn't apply in time, I won't be able to start college this fall.
⇒ This is able Definition #3; capable is not appropriate here.
Melvin is a lazy student; he isn't capable of finishing college.
⇒ This is capable Definition #3; able is less appropriate here.
Dorothy doesn't know what she is doing; she isn't capable of holding the meeting today.
⇒ This is capable Definition #1; but able might be appropriate here.
Best Answer
One difference is that inspiring always means that someone is actually inspired by it, whereas inspirational can also be used in compounds where it means only that something is intended to inspire; an inspirational speaker (or "motivational speaker"), for example, is someone whose job is to give speeches that are intended to inspire, without regard for whether they succeed (so "boring inspirational speaker" is not a contradiction in terms), and similarly, an inspirational poster (or "motivational poster") is a poster that is (supposedly) intended to inspire positive qualities, but I don't think it generally succeeds. But this use is non-predicative; in "the speaker was inspirational" (predicate adjective) or "a very inspirational poster" (modified by very), that meaning is not available, so in these cases inspirational just means inspiring.