Gas lift lightens the column by injecting gas. An electric submersible pump, a beam pump, a progressing-cavity pump, or a jet pump adds pressure to the liquid. The choice follows the rate, the gas fraction, the depth, the deviation, the temperature, and whether the well makes sand.
Lift does not add reservoir energy. It spends surface energy, compression or electricity, to reduce the flowing bottomhole pressure the reservoir has to push against. A lift design that ignores free gas will gas-lock a pump or over-inject a gas-lift well. A design that ignores sand will destroy the downhole equipment.