These four words are synonymous when used like this: My arm is sore. My arm is painful. My arm hurts. My arm aches.

A pain and ache is something that hurts example Pain and Ache are usually interchangeable I have a "pain" in my arm! I have a "pain" in my leg, what could be wrong? I am having really bad back "pains" - This usage has an -s added to the end because it's plural. while hurt is used like so You hurt me John! This means to inflict pain on someone when used like this but if you said You pain me John! it just doesn't mean the same thing or sound right. I got hurt playing on the slide. Sore can be used in several ways I have an open sore on my leg. This means that the wound or trauma site is still open. Or can even mean a pimple etc. I am so sore. Used in this way sore means that you are hurting all over or just in one spot.