Another distinction is "can" versus "may". Can is often used instead of may, but technically is about capability. So, if you ask a professor in class "Can I go to the bathroom?" your professor might jokingly say "I hope you CAN but no you may not!". Can = capability May = permission

Hi Adrian, The sentences should look like this: May I ask you a favor? Could I ask you a favor? And they mean the exact same thing. Make sure to note that I corrected the spelling of the word "ask".

May is more polite. Could is a less formal way of asking. Like for a senior, but not a teacher