Why is in phagocytosis it is called 'food vacuole' but in pinocytosis is

Well,
Phagocytosis is because the vesicle is fused with lysosomes containing hydrolytic enzymes. The enzymes break down the contents of the (now) 'phago-lysosome' and release the useful products within the cell. Henceforth, the contents of vacuole actually serve as a means of providing nutrients and thus called 'food vacuole'.

Pinocytosis is used for the intake of liquid/fluid susbtances. As the vacuole formed is largely to take in the liquid and then release inside the cell, it can be called a secretory vacuole. Are ou sure about the pinocytic vacuole?

Hope it helps