Basically, a lot of the gas that has been blown off becomes 'lit up' to glow as a bright nebula. However, there is a distinction between high mass stars and really high mass stars. These LBVs suffer outbursts and eject large amounts of mass. He stars with high mass loss. These then explode as SNe.
All stars have mass loss.
Have thermal winds resulting from gas that 'boils' away in a hot corona. Usually have higher mass loss. Mass loss is driven by the high luminosities. Winds are important for two reasons. First a star's mass determines its evolution and eventual demise.