Bicycle Crank Arm: It connects the pedal to the bottom bracket and, through the axle, transfers motion to the drivetrain system.
Bicycle Crankset: The complete front transmission system that includes the crank arms and chainrings, transferring motion from the pedals to the chain.
Bicycle Chain Rings: The front chainring attached to the crankset. It has teeth where the chain sits and transfers power from the pedal to the drivetrain. It can have from 1 up to 3 chainrings.