A Salvage Title and A Rebuilt Title are in a way Similar but A Salvage Title is issued to a vehicle that has been totaled and deemed to be unsafe for the road.
When the vehicle with a Salvage Title gets rebuilt to be road worthy and safe again the vehicle once it passes inspection can be issued a rebuilt title meaning it's passed inspection and is now road worthy again.
Although having a Salvage Title doesn't always mean the vehicle is not safe to drive so a Salvage Title isn't always bad.