Rolls are similar to flips in the fact that they are a complete rotation of the body, but the rotation of the roll is usually made on the ground while a flip is made in the air with the hips passing over the head and without any hands touching the ground.
[1] The forward roll (colloquially called a roly poly) is one of the most basic elements in gymnastics and one of the first learnt.
The hands then push the floor strongly and straighten their arms and continue to rotate their body over their head.
The gymnast then rolls onto their side and does a complete rotation of the body, remaining parallel to the performing surface.
The gymnast then folds more tightly until they roll over their back and return to a sitting straddle position.
It is considered an advanced forward roll, demonstrating flight and a smooth landing.