what is the difference between ascent of sap and transpiration pull?
Ascent of sap: It is the movement of water and minerals from the roots to the aerial parts of the plant through xylem tissue.
Transpiration pull: Due to evaporation of water from the cells present on the surface of the leaves (transpiration) a vacuum space is created. To fill that vacuum water droplets from the other cells rush inside. This rush of water towards the vacuum creates a mechanical force that enables to pull up water absorbed by the roots through the stems. These antis gravitational force that results in upward movement of water through the xylem is known as transpiration pull. In tall trees transpiration pull can draw water up to 50 meter height.