Will and Can Questions

These two words have different meanings am I right? I have a way of bypassing "can" questions which can be very annoying. Unless you do not have the ability to give them their desires of what they want? You can give them their desires. But the real question is, will you? Here is where will kicks in. If the person asking the question says a will question, you have a choice of yes or no. This is if you feel like it but on the other hand with "can" you don't have the choice but you can be sneaky and still deny them. If they ever say a can question, say, "I can, but will I?" Unless you really cant.