Vishal, I am not sure about any such preference on the GMAT but here is the most commonly agreed on difference.
Compared with is used when comparing two things.
When they compare apples with oranges, many people find that they like both.
In his essay, John compared the parties held by ancient Romans with parties held today.
In the article, the newest Japanese cars are compared with the newest German cars, and the conclusions are surprising.
Compare to is used to make the point that one thing is like another. Compare to essentially means the same thing as liken to.
The wild parties held at the university have been compared to those held in ancient Rome.
(The wild parties held at the university have been likened to those held in ancient Rome.)
I hesitate to compare my own works to those of someone like Dickens.
As I said, I am not sure whether the GMAT sees things that way.