hooke/stiffness model

on doc page for gran model hooke/stiffness given description is

{
gran model hooke/stiffness

Syntax:

model hooke/stiffness [other model_type/model_name pairs as described here ] keyword values

zero or more keyword/value pairs may be appended to the end (after all models are specified)

absolute_damping values = 'on' or 'off'
on = activates tangential damping
off = no tangential damping
limitForce values = 'on' or 'off'
on = ensures that the normal force is never attractive (an artefact that can occur at the end of a collision).
off = standard implementation that might lead to attractive forces.
tangential_damping values = 'on' or 'off'
on = activates tangential damping
off = no tangential damping
}
I want to ask that what is the difference between absolute_damping and tangential_damping if both are doing tangential damping on/off.

Regards