Pail means a round container that is open at the top and usually has a handle: “I have returned the plastic pail to the shop-keeper because it had a small hole in the bottom and so it could not hold water.”
Pale on the other hand, has the following meanings:-
1. Light in color: “The walls of the room looked beautiful painted with a pale blue color.”
2. Having a skin color that is closer to white than is usual or normal: “The child looked pale with fear on finding himself alone in the dark room.”