According to Wikipedia, there are 5 different types of tequila:
Blanco (white) or plata (silver): white spirit, un-aged and bottled or stored immediately after distillation, or aged less than two months in stainless steel or neutral oak barrels
Joven (young) or oro (gold): usually a mixto (rarely 100% agave) with added coloring
Reposado (rested): aged a minimum of two months, but less than a year in oak barrels of any size
Añejo (aged or vintage): aged a minimum of one year, but less than three years in small oak barrels
Extra Añejo (extra aged or ultra aged): aged a minimum of three years in oak barrels.