"The Vineyard" is a symbolic spiritual "Planting" of God, His bequeathed "Vineyarders", i.e. people who have a holy faith in the Truth of His Holy Will, who have realized the need to live in righteousness by following His Commandments and who have exalted spiritual qualities.
"Vineyard" are people who need the spiritual guidance of the Truth of God's Will - the "Vineyarder", its fulfillment.