What is the difference between an aquifer and an aquitard? View Available Hint(s) What is the difference between an aquifer and an aquitard? An aquitard is a rather permeable rock, whereas an aquifer is an impermeable rock. An aquifer is a rather porous rock, whereas an aquitard is a rock with very low porosity. An aquitard is a rather porous rock, whereas an aquifer is a rock with very low porosity. An aquitard is a rather permeable rock, whereas an aquifer is a rock with very low porosity. An aquifer is a rather permeable rock, whereas an aquitard is an impermeable rock.