When a body travels or covers or moves equal distances in equal durations of time, then the body is in uniform motion.
when a body does not cover equal distances in equal durations of time, then it is in non uniform motion.
when the velocity of a body increases at a constant rate in time, then it has a constant or uniform acceleration. The increase in the velocity of the body is proportional to the time duration. The changes in velocity are equal in equal durations of time.
acceleration is a constant wrt time.
When the changes in velocity are not equal for equal durations of time, then the body is in non uniform acceleration. This means that the body has different accelerations during different time instants. Here acceleration is not constant wrt time.