What is the difference between discharge head and suction lift in pumps?

Generally, the pump will be situated (located) someway between suction source point and outlet discharge point. Suction lift is the distance (elevation) between suction source point and the inlet of the pump. Discharge head is the distance (elevation) between pump location and discharge outlet point.

The most critical is the suction lift. The lift should never cross about 10 m. Because of this limitation, in many irrigation wells, the pump is located inside the well. And many wells will have two locations; one at lower level, to be used when the water level is very low and the other at higher level when the water level is high (during rainy season). If the pump is located at lower level and if the water level in the well is increasing, then the pump should be relocated at the higher level.

If the discharge head requirement is high, it can be managed with selecting a pump having higher impeller diameter.

As locating a pump within 10 m of a source point is very difficult in the case of bore wells, submersible pumps are used in such cases.

When the horizontal distance is relatively long, it would be better to go for a larger diameter pipe.