All of them roughly express the same thing. > My hair stood up on end. Is past tense (it happened before now) and doesn't really work well in the present tense (if it's happening right now). > I've got goose bumps. Is American English > I've got goose pimples. Is British English.

Yes, they mean the same thing. And another word that means the same thing is "gooseflesh." All of them refer to the same physiological process, which contracts the _arrector pili_ muscles around the base of each hair, which has the double effect of raising a little bump and making the hair stand on end.

As far as I know, goose pimples is not a common term in the United States. goosebumps is used when someone is excited or scared. Often times, beautiful music can make people say "wow, that gives me goosebumps!" OR a chilly breeze can give you "goosebumps." "The hair on the back of my neck stood up" OR "It made the hair on the back of my neck stand up": This phrase is used more often when speaking specifically of fear..

Yes, no one really uses the word "goose pimples".