Lets put it this way - if you can walk on it WITH OUT dissociating and or getting dizzy then it may be just a sprain .. course some sprains are also very painful.

another way to tell is that the foot turns a VERY blackinsh purple and the toes feel as if you have sat with your foot in the same position ling enough for it to go numb and then the pins and needles effect.

As for the break itself That depends on the type of break.. hairline fractures are basically like a crack in the bone. the two sides of the crack are still touching but on x ray you see a crack line. you cant feel any difference from outside by touching the spot.

a clean break is when both parts of the bone are separated but the edges are straight and will naturally fuse back together with out a lot of problems as long as the bones remain lined up and as close to each other as possible. when rubbing your fingers over the break you will feel the space between the bone. that is if you can get past the pain of touching the area. In order for me to rub my foot when I broke it I had to be semi dissociated (in my tunnel area) otherwise it hurt to even get close to it.