I think I understand the difference. Could you explain? You are right, this is a mask.
Mike,
Similar to a mask, but not really.
A stencil is made in such a way as to hold all letters together without the need of "transfer paper."
Some can be used repeatedly for a long period of time. Some can be cleaned to remove paint buildup.
Material is needed to hold the inside of letters together like the "A", "B", "P," etc. For this to happen, you see separations in the painted stroke.
There's a stencil Font. "Some" lettering with this Font was used on military aircraft for numbered markings.
A good example is on the sides of shipping crates.
A worker would place the stencil, generally made of a thin stiff mylar or coated cardboard, against the surface and with an aerosol can or spray guy, apply paint.
Take the stencil away and go to the next crate.
Charles