Hash is a traditional term for concentrate that uses a specific method of collecting the resin from the plant. Oftentimes you can use the two words interchangeably, however concentrates can include things other than hash, such as oil and kief. Hash is the resin that is collected by harvesting the trichomes from the bud of the flower. Traditionally, hash was collected by hand and rolled into balls that contained some of the plant parts such as the trichomes. But techniques today use a purer method that completely removes the plant material.