Model rocketry
small rockets, small motors.
A-D motors, typical rocket size=1"-3'
motor size=3/4" to 3,1/2"
typical worries: losing your rocket
MPR rocketry
medium rockets, medium rocket motors.
E-G motors, typical size=3'-7'
motor size=2.5" to 8"
typical worries: your rocket failing or flying too high and losing it.
HPR rocketry
BIG rockets, Huge motors
H+ motors, typical rocket size range=6'+
typical worries: causing damage to the surrounding area, rocket failure