Ph deals with how basic or acidic your water is. It measures on a scale of 0-14, 7 being neutral. Anything below 7 is acidic, anything above 7 is alkaline. Hardness deals with the amount of dissolved carbonates (mostly calcium, lesser degree magnesium) in your water. The greater the amount of dissolved carbonates, the harder your water is. Although its a bit more complex to explain, the more dissolved carbonates/harder the water generally the ph will be more alkaline.