Although folk country and bluegrass music share several musical instruments in common there's one instrument that is widely used in country music and almost never used in folk or bluegrass which one is it

Although folk country and bluegrass music share several musical instruments in common there's one instrument that is widely used in country music and almost never used in folk or bluegrass. This instrument is the pedal steel guitar.
Both folk country and bluegrass are traditional country music.The difference is that bluegrass relies mostly on acoustic stringed instruments.

We need to see the sculpture

What are the terms cause i might know it