WHAT IS THE DIFFERENCE BETWEEN CONSTANT SPEED AND UNIFORM MOTION ?

Uniform Motion is defined as the type of motion in which the speed of the body moving in a straight line ( i.e. velocity) remains unchanged over a period of time. So, it is unaccelerated motion. An object moving along a straight line with constant velocity, say 60 km/hr would posses uniform motion.

Constant speed means covering equal distances in equal intervals of time by body moving along any path (straight , curved or circular). It means speed is same through the motion.

For ex. an object moving along circular path with a constant speed.