In short...
Accelerated = increased spin rate - you either flattened the spin or "wound it up" and accelerated the rate of the turn.
Crossover = "crossover spin" in aerobatics in which a pilot is too exuberant in the recovery of a spin and causes an inverted spin in the other direction.
Both are very dangerous - usually because you don't realize what you did to create the bigger mess you just got yourself into.
Training Training Training will teach you to identify and recovery from whatever flavor of spin you happen to find yourself in at the time.
"... identify and recovery from whatever flavor of spin you happen to find yourself..."
Nose down, prayers up works for me.