what are the differences between medical ,clinical and sports massage therapy?

[Tom]

i want to become a massage therapist and ive looked at massage therapy programs and most say they teach u a little of all three types and i think i have to choose one to follow through with as a "major" for lack of a better term. what im curious to know is : what is the difference in the three "majors" ? forinstance is there a difference in work invironment? and what a massage therapist would do in each of those catagories.