Pittsburgh Pirates

Full Season
+ Class AAA is the highest professional league below MLB and is comprised of veterans and prospects, many of which already have MLB experience.
+ Class AA is generally a prospect league with more advanced/older prospects who are within reach of the Major Leagues.
+ Class A+ (or Advanced A) is a 2nd or 3rd year stop for prospects. Some top-level college players will start their career here.
+ Class A is a player's first foray into a full 140-game season. College and High School players don't play anywhere near this number of games in amateur baseball and so there might be some adjustment

Short Season
+ Class A- (or short Season A) is a level above Rookie and is comprised of 2nd year players or more advanced players who were recently signed out of the draft. The season does not begin until mid June
+ Class Rookie is the starting point for players in a minor league season. These are short-season leagues with 1st and 2nd year players. Players at this level are often around the same age. The Rookie levels are further divided into advanced Rookie leagues and complex leagues. Complex leagues are where players further hone their skills and where no admission is charged for games.