The pressure on that small pump my vary, but those numbers are to tell the buyer if it is a low pressure pump or high pressure one. the pressure could vary because of things like; how high the pump has to pump the fluid , filters in the line, types of fuel, size of the fuel line, number of connections and elbows, atmospheric pressure , ect. There is allot to consider, if pressure is important. Also the pump itself . The manufacturer is saying , the pump will put out at least “x” pounds, but not more than “y” pounds of pressure. according to how well that particular pumps part fit and work together. Hope this helps.
