What you may have seen called “sauce” looks like a large crystals swimming in a darker liquid. That isn’t a full spectrum extract. Little chunks of bright white and yellow diamonds swimming in a pool of gold liquid or just the gold liquid are the only two consistencies of full spectrum extracts.
Rosin is solventless technique, meaning the process does not require use of any foreign substances. Instead, rosin uses a mechanical process involving heat and pressure to extract the resin from the plant.