The difference between "can" and able to do is simple. With can, you are using your authority whereas with be able to do, there's no authority that means any body can say I will be able to do such and such things but there's no authority. Hope this helps.
There is no difference because un- means not, so if it is put together with able it will mean not able.
Would=if he wanted to Could=if he was able to
I think its just the wording that is different. The meaning is the same.
The difference between free and economic goods is the fact that, free goods don't cost us anything to be able to have and economic goods cost us to be able to get that service or good.
Discernment is a gift from God to be able to tell the difference between something that is from God and something that is not from God. To be able to tell the difference between good spirits and demons, to be able to tell good thoughts from bad thoughts, and good influences from bad influences.
"you may" means that you have permission ( to do something) . "you can" means that you are able (to do something).
Capability means you "can" do it. Feasibility means you "might be able" to do it.
Can states something is able to be done. Will implies something is going to be done.
Correlation and causation.
A muggle like you wouldn't be able to understand.
able and allowed?
Infants do not walk yet. Toddlers are able to 'toddle' about on their legs.