Cilia and flagella are hair-like, extremely thin, delicate microscopic structures found on the outer surface of the cell. Basically both have a similar structure but cilia are small-sized and numerous, while flagella are long, whip-like and fewer (usually one or two in a cell) in number. Both of these originate from centrioles or basal granules and are composed of microtubules.
Functions
They are locomotory organells of the cell. In the internal cavities of animals, the lining of cilia helps in the movement of liquids.