Question

What is pollination? how does self pollination differ from cross pollination?

Answer 1

Pollination is the transfer of pollen grains from the stigma to the anther of either the same flower or another flower........
Self Pollination is the transfer of  pollen grains from the stigma to the anther of the same flower..........
Cross Pollination is the transfer of  pollen grains from the stigma of a different flower to the anther of a different flower.........
Both happen by either insects or the wind.

Answer 2

its the transfer of pollen from anther to stigma....
in self pollination ,transfer happens with in the flower but in cross pollination the transfer happens from anther of one flower to stigma of another flower