You use a suction bulb to gather a specific amount of the liquid when using a pipette, and you can push the bulb down to let the liquid out. So, you can control the amount of liquid in a pipette.
But with the burette, you open the tap to let the liquid out and close it if you want to stop. But you cannot control the amount of liquid in it.
Hence a pipette is more accurate. Both are commonly used in titration, which is a method used in chemistry to determine the molarity of an acid or a base.