The Romans made copies of original works of Greek art as the Romans came after the Greek and they wanted to show themselves more powerful than Romans.
There was lot of differences between Roman wart work and mainly different from the technical point of view. The Greeks believed that art was an expression of perfection. They tried to encode the true physical appearance of their objects in the artwork.
The Greeks represented the ideal form of beauty, physical strength, and power through their work of art while Roman art work was more practical and that artwork used for the purpose of decoration.
