what is the difference between rate of percolation and the amount of water retained?

percolation refers to the amount of water seeping down . while amount of water retained refersto the amount of water held . suppose you pour 1 000 M L of water in  the soil  out of which 600 ML seeps down . so we can say that

amount of water retained = 400 ml

amount of water percolated = 600 ML

HOPE ITS CLEAR !!!