Compression stockings and support hose both serve the same basic function. When worn, they provide pressure from foot to knee (and sometimes thigh) to promote proper blood circulation. The pressure is greater at the foot and gradually lessens the higher up the leg the stocking goes.
The level of pressure is a measurable feature purposefully established by the maker for relief from medical issues that range in severity. Generally speaking, the more severe the issue, the more pressure is required from the stocking.