The size of the junior hacksaw is 150m (6”).
The difference between a junior hacksaw and a coping saw is that the coping saw has the blade facing the handle of the hacksaw, whereas the junior hacksaw is pointing away from the handle.
Junior hacksaws are commonly used for cutting through metal pipes or plastic tubing. The blade of a junior hacksaw is much smaller than a regular one, so it can be used for more precise cutting that requires a neater finish.
A junior hacksaw can be used for more precise cuts or when space is limited.