To understand what buoyancy is better, I guess it would be necessary to first explain what buoyant force is. Buoyant force, in physics, is described as an upward force exerted by liquids to force any substance in it to rise upwards.
It closely relates to buoyant force.
Definition of buoyancy: Buoyancy is the ability or tendency of a substance or object to float or rise in a liquid because of the buoyant force of the liquid acting upon it.
In conclusion - buoyancy of a liquid is a result of the buoyant force acting.
So, a liquid's buoyancy is caused by buoyant force.