What is the difference between centre of gravity,centroid and centre of mass ?

Centroid is the geometric centre of a plane figure or object

Centroid divides the shape into regions of equal moments.

 

 

Centre of mass is the mean location of all masses in a system

 

Centre of gravity is the point through which the weight of a body acts.

 

All these will coincide for a plane figure with uniform density and uniform distribution of mass