It comes to the same thing. We Protestants get a divorce from the state whilst Catholics get an annulment from their Church.

The Catholic Answers

There is all the difference in the world between the two positions. A civil divorce claims to break the bonds of a valid marriage, bonds which the Catholic Church rigidly declares to be unbreakable. A decree of nullity does not break the bonds of a valid marriage at all. It declares that the marriage was never a true marriage and that there is no bond to break. It declares that the reputed marriage was null and void as a contract from the beginning. Had it been valid, the bond could not be broken save by the death of one of the parties.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty