Float Shoe: when landing the casing, the drill fluid have no resistance to float shoes. The pressure of circulating mud make the valve head down a displacement, the disc of valve rod's end will fall off automatically; after stop pumping, the valve press the valve seat upwards under the action of spring, the float valve becomes one-way valve. So that can pump the drilling fluid and cement slurry into it from up to down, but the fluid in the casing or outside casing annulus can't be return to prevent from back flow.

Float Collar: the using method is the same as float shoes except the lower end is pin. It is connected with casing. The usage of float collar is to make the casing landing easily by reducing the loading. When landing the casing, make sure to prevent from the drill fluid flow into the casing. After cementing, the float collar can prevent the cement slurry returning to the casing.