Extended spring training is when each manager says "Hey I got 3 guys that need work, and we just signed this one guy out of the Mexican league and our GM wants to give him 2 innings." So they play to get extra pitchers work. Minor league rosters can get packed sometimes with the normal everyday career minor leaguers, the bonus babies that need development, guys just signed that need looks, and big leaguers down for rehab or spot starts for work. So they play a couple extra. Different minor league levels report at different times. You got rookie ball, low A, A, high A, double A, triples A, extended season A, short season A. When the college guys get their seasons over with they report a month after to short season A, so it's kind of spring training for those guys. You got the draft in early June, etc. But there is only 1 real deal spring training which is the one we all know.